Patch Tuesday - September 2026
Microsoft's September 2026 Patch Tuesday fixes 999 CVEs, a record, with two zero-day privilege escalation flaws already exploited in the wild.
Microsoft published 974 own-product vulnerabilities plus 25 non-Microsoft CVEs, totaling 999 — the most CVEs Microsoft has ever released in a single day. Two flaws are exploited in the wild: CVE-2026-85880, an out-of-bounds write in Windows ALPC granting SYSTEM privileges, and CVE-2026-81963, an improper link resolution flaw in the Windows Update Stack also leading to SYSTEM. Chrome's V8 zero-day CVE-2026-85046 was patched in Edge on September 2, but Microsoft had not published a corresponding advisory, leaving uncertainty about other Chromium fixes in Edge. October 14 lifecycle changes end servicing for Windows 11 24H2 Home/Pro, Office 2021, and Exchange Server 2016/2019.
CISA KEV: Google Chromium V8 Type Confusion Vulnerability — Google Chromium V8 (CVE-2026-85046)
CISA added actively exploited Chromium V8 type confusion CVE-2026-85046 to the KEV catalog, requiring federal mitigation by September 18.
CISA added CVE-2026-85046, a type confusion vulnerability in Google Chromium's V8 JavaScript engine, to the Known Exploited Vulnerabilities catalog. The flaw allows a remote attacker to execute arbitrary code inside the browser sandbox via a crafted HTML page and affects Chromium-based browsers including Google Chrome, Microsoft Edge, and Opera. Federal agencies must apply vendor mitigations by 2026-09-18 under BOD 26-04; CISA notes known ransomware campaign use is currently unknown.
CISA Warns of Chromium Type Confusion 0-Day Vulnerability Actively Exploited in Attacks
CISA added the actively exploited Chromium V8 type confusion zero-day CVE-2026-85046 to its KEV catalog, urging patching of Chrome, Edge, and Opera.
CISA added CVE-2026-85046, a V8 type confusion flaw (CWE-843) in Chromium-based browsers, to its Known Exploited Vulnerabilities catalog. A remote attacker can trigger arbitrary code execution inside the browser sandbox via a specially crafted HTML page. Google Chrome is directly affected, and Microsoft Edge, Opera, and other Chromium-based browsers may also be impacted depending on their V8 version. Google has released a Stable channel Chrome update, and CISA directs mitigations under Binding Operational Directive 26-04.
Attackers are weaponizing the gap between Chromium fixes and Chrome patches
Espionage actors use the BlueMoon exploit kit to chain Chrome V8 and Windows kernel zero-days via spear phishing, gaining full admin on unpatched endpoints.
Proofpoint, working with Google Threat Intelligence Group, Microsoft Threat Intelligence Center and Volexity, reports that the BlueMoon exploit kit chains V8 type confusion CVE-2026-85046, V8 sandbox escape CVE-2026-87491 and Windows kernel LPE CVE-2026-85880, all rated high severity. The V8 flaws were fixed in upstream Chromium source but had not yet reached Chrome stable releases, creating a patch gap that attackers reverse-engineered and weaponized. A China-aligned state-sponsored actor used the kit from August 28 against a small number of US NGOs, mining and commodity trading firms via rapport-building spear phishing, and within days several mostly China-linked espionage clusters adopted BlueMoon. The chain yields full Windows admin privileges from a single phishing click; defenders should patch Chrome and Windows, apply Proofpoint detections and hunt for leftover artifacts.
AmnesiaStealer Hijacks Chromium Sessions to Give Attackers Live Browser Control on macOS
Jamf details AmnesiaStealer, a new Rust-based macOS infostealer that hijacks Chromium sessions for live attacker-controlled browser access and steals Keychain data.
Jamf Threat Labs disclosed a three-stage macOS infostealer called AmnesiaStealer distributed via a fake GitHub download page using a ClickFix-style lure that tricks users into pasting a Base64 command into Terminal. The Rust payload harvests the Keychain, Apple Notes, Telegram sessions, Safari cookies, and 16 Chromium-family browsers, and captures the system password via a native prompt validated with dscl. A remotely fetched stream_module gives operators hidden, interactive browser control via the Chrome DevTools Protocol, streaming a live session at roughly 3fps. It persists via a root LaunchDaemon impersonating Apple's crash reporter and leverages the TCC bypass CVE-2020-9771 against macOS Catalina.
The extension you never installed: KREMLIN forges Chrome's own integrity checks to steal banking sessions
Elastic details KREMLIN, a Brazilian banking malware whose malicious Chrome/Edge extension forges Chromium integrity checks to steal sessions.
Elastic Security Labs tracked operation REF9334 and its KREMLIN toolkit, a Brazilian banking malware campaign impersonating twelve banks across seven campaigns since May 2025. The infection chain uses multi-stage obfuscated JavaScript loaders with sandbox checks (file and process counting), scheduled-task persistence, and an Ethereum smart contract acting as a dead-drop resolver for C2 and payload URLs, abusing Archive.org for hosting. The malicious browser extension bypasses Chromium integrity mechanisms by manipulating Secure Preferences and regenerating required HMACs and App-Bound encrypted hashes. Threat Command disrupted over 1,500 infections by registering the kill-switch canary domain.
Novel Blue Moon kit targeting Chrome and Windows reflects new reality of AI-driven exploits
Proofpoint reports the BlueMoon exploit kit, chaining two Chrome V8 zero-days and a Windows ALPC bug, being shared across China-linked espionage groups.
Proofpoint identified a new exploit kit, BlueMoon, first observed on August 28 and used by TA412 (APT31/Violet Typhoon) against US NGOs, mining firms, and commodity trading companies. The kit chains a V8 type confusion RCE (CVE-2026-85046), a V8 sandbox escape, and a Windows Advanced Local Procedure Call privilege escalation (CVE-2026-85880), both patched flaws having been exploited in the wild. At least four espionage groups, most with suspected China nexus including UNK_LateNight, adopted the kit within days, targeting US aerospace firms with defense-sector lures. Fewer than 20 organizations were observed targeted, and researchers believe AI-assisted exploit development against upstream Chromium patches enabled the kit's rapid creation and sharing.
⚡ Weekly Recap: VMware Exploits, Windows 0-Day, MCP Attacks, Browser Hijacks and More
Weekly recap: suspected China-nexus APT exploited VMware vCenter CVE-2026-59310, Lazarus used Windows zero-day CVE-2026-68820, and macOS flaw dropped Monero miners.
The week's top stories included a suspected China-nexus APT exploiting VMware vCenter CVE-2026-59310 (CVSS 9.8), a directory-traversal flaw enabling arbitrary code execution, with backdoors, reverse SSH and Babuk-derived ransomware deployed, per QUIRSO. NCSC-NL reported active exploitation of macOS Screen Sharing flaw CVE-2026-65400 (CVSS 9.8) to install Monero miners on systems with port 5900 exposed. Lazarus Group exploited Windows zero-day CVE-2026-68820 (CVSS 7.0) in Operation Dream Job, delivering ForestTiger and Troy backdoors to defense and aerospace targets. GeoServer patched a critical SQL injection flaw exploited within hours of disclosure, and Jamf analyzed the new Amnesia Stealer for macOS with live browser control.
U.S. CISA adds Cisco, Google Chromium V8, Fortinet, and Citrix NetScaler flaws to its Known Exploited Vulnerabilities catalog
CISA added actively exploited Cisco FMC, Chrome V8, Fortinet and Citrix NetScaler flaws to its KEV catalog, ordering federal patching by September 12.
CISA added four actively exploited vulnerabilities to its Known Exploited Vulnerabilities catalog. CVE-2026-20079 (CVSS 10.0) is an unauthenticated authentication bypass in Cisco Secure Firewall Management Center's web interface enabling script execution and potential root access. CVE-2026-87491 (CVSS 8.8) is an out-of-bounds write in Chrome's V8 engine — the seventh actively exploited Chrome zero-day of 2026 — fixed in Chrome 153.0.8010.36. CVE-2025-25249 (CVSS 8.1) is a heap-based buffer overflow in FortiOS/FortiSwitchManager's cw_acd daemon being exploited with the PivotC2 RAT, and CVE-2026-19490 (CVSS 9.3) is a NetScaler SAML HTTP-Redirect authentication bypass; federal agencies must patch by September 12, 2026.
Chinese espionage groups swarm to exploit triple-link chain of zero-days
At least four China-aligned espionage groups chained three zero-days in Chromium browsers and Windows ALPC for espionage since late August.
Proofpoint observed at least four state-aligned threat groups, starting with TA412/Violet Typhoon/APT31 on August 28, chaining three zero-days in the 'BlueMoon' exploit chain targeting Chrome, Chromium-based browsers and Microsoft Windows. The chain includes RCE flaws in Chromium's JavaScript engine (CVE-2026-85046, CVE-2026-87491) and a Windows Advanced Local Procedure Call privilege-escalation zero-day (CVE-2026-85880), enabling sandbox code execution, sandbox escape and system privileges. APT31 delivered the chain via phishing links to NGOs, mining and commodity trading firms in the US, installing a browser extension disguised as Google Gemini to surveil activity and steal credentials. Other groups (UNK_LateNight, UNK_DoubleCheck, UNK_QuietRacket) targeted US aerospace, Vietnamese manufacturing, and Indonesian and Singaporean organizations; fewer than 20 victims were directly observed but the true count is likely higher.
U.S. CISA adds Google Chromium V8 flaw to its Known Exploited Vulnerabilities catalog
CISA added actively exploited Chrome V8 type-confusion flaw CVE-2026-85046 (CVSS 8.8) to its KEV catalog; Google patched it in Chrome 152.
CISA added CVE-2026-85046 (CVSS 8.8), a V8 type confusion flaw, to its Known Exploited Vulnerabilities catalog, requiring US federal agencies to patch by September 18, 2026. Google fixed it in Chrome Stable 152.0.7977.82/.83 for Windows and Mac and 152.0.7977.82 for Linux, alongside 11 other vulnerabilities. The bug lets a remote attacker execute arbitrary code inside the browser sandbox via a crafted HTML page and is the sixth actively exploited Chrome zero-day of 2026. Researcher Salvatore Gulizia (Serotav) reported it on August 4, 2026.
China-Linked Hackers Exploit Sogou One-Click RCE to Deploy GRAYRABBIT Backdoor
China-linked UNC3569 exploited CVE-2026-51990 in Sogou Input Method to deploy the GRAYRABBIT backdoor in active espionage intrusions.
Gen Threat Labs discovered UNC3569 exploiting CVE-2026-51990, a one-click RCE in Tencent's Sogou Input Method for Windows that chains an insecure sgbiz: protocol handler with an unsandboxed Chromium 80 CEF webview. The chain weaponizes CVE-2021-38003 (V8 type confusion) to run shellcode that DLL-sideloads via 7z.exe/7z.dll and deploys the GRAYRABBIT backdoor, which beacons over RC4-encrypted raw TCP 443 to mail.uaiubifas[.]top. Tencent patched the issue in version 16.3.0.3498, released via automatic updates on April 21, 2026. UNC3569 is a PRC-nexus espionage actor targeting government, education, technology, and financial sectors across East and Southeast Asia.
China-Linked Hackers Exploit Chrome and Windows Zero-Days in BlueMoon Attacks
China-linked clusters deploy the BlueMoon kit chaining Chrome V8 CVE-2026-85046 and Windows LPE CVE-2026-85880 in espionage campaigns.
Proofpoint researchers identified BlueMoon, an exploit kit combining a V8 type-confusion RCE (CVE-2026-85046), a V8 sandbox escape, and a Windows kernel privilege-escalation flaw (CVE-2026-85880), first observed August 28, 2026. At least four clusters adopted it, led by TA412 (also tracked as APT31/Violet Typhoon) and followed by UNK_LateNight, UNK_DoubleCheck, and UNK_QuietRacket, targeting aerospace, manufacturing, government, consulting, and financial sectors. The kit exploited a nearly four-week patch gap between the public Chromium commit (August 7) and stable rollout (September 3). TA412 delivered the GemStone Chrome extension masquerading as a Gemini companion, while other clusters deployed ShadowPad via DLL sideloading, a Rust loader, and DoH-based C2.
Four groups caught using the same Chrome and Windows exploit kit
Proofpoint reports at least four hacking groups, some China-linked, share the BlueMoon exploit kit chaining Chromium and Windows kernel vulnerabilities to install malware.
Proofpoint named the nearly identical kit BlueMoon; it chains two Chromium vulnerabilities with one Windows kernel privilege-escalation flaw affecting Windows 10 (October 2018 Update and 2004), Windows Server 2019 and 2022, and the initial Windows 11 release. All three vulnerabilities received patches within 24 hours of the activity. The kit is being actively used by at least four hacking groups, some with Chinese government ties. Proofpoint links the rapid, visible sharing of a historically rare full browser exploit chain to the Chromium supply-chain patch gap and AI-assisted exploit development.
4 groups caught using the same Chrome and Windows exploit kit
Proofpoint says at least four groups, some China-linked, actively share the BlueMoon kit chaining two Chromium and one Windows kernel exploit.
Proofpoint researchers report that at least four hacking groups, some with ties to the Chinese government, are actively using a nearly identical exploit kit named BlueMoon. The kit chains two Chromium browser vulnerabilities and one Windows kernel flaw affecting Windows 10, Windows 11 initial release, and a later Windows version to install malware of the attacker's choice. All three vulnerabilities received patches within the past 24 hours. Proofpoint attributes the kit's rapid, widely shared deployment to a Chromium patch-gap window and AI agents accelerating exploit development against publicly accessible upstream patches.
KREMLIN Banking Malware Bypasses Chrome Security to Steal Banking Sessions
Elastic Security Labs details KREMLIN, a Brazilian banking malware that implants malicious Chrome and Edge extensions by forging Chromium integrity values to steal banking sessions.
Elastic Security Labs tracks the KREMLIN banking malware operation as REF9334, active since at least May 2025 across seven campaigns primarily targeting 12 Brazilian banks. The malware is installed by a victim-run JavaScript loader, achieves scheduled-task persistence, and side-loads a malicious DLL via SentinelOne's SentinelMemoryScanner.exe. It modifies Chrome and Edge Secure Preferences files, enables developer mode, and regenerates Chromium MAC values to silently install extensions, while extracting browser encryption material including the newer App-Bound OSCrypt key. An Ethereum smart contract serves as a dead-drop resolver for C2 config; Elastic disrupted over 1,500 infections via a canary domain.
One Exploit Chain, Two Espionage Campaigns: Chrome and Windows Under Fire
Two China-linked APT groups reused identical Chrome/Windows zero-day chain against NGOs, deploying GRIMWIDGE backdoor and LONGTALE credential-stealing extension.
Volexity reports that China-linked actors UTA0560 and JungleBamboo (APT31/TA412) ran byte-identical Chrome/Windows exploit chains against NGOs starting September 1, 2026, combining Chrome type confusion CVE-2026-85046, WebAssembly sandbox escape CVE-2026-87491, and Windows kernel flaw CVE-2026-85880. The Chrome bug was fixed in Chromium source but not yet shipped to Chrome users, making it an effective zero-day with an unusual patch gap. UTA0560 delivered the in-memory GRIMWEDGE JScript backdoor, while JungleBamboo deployed the SUPERSTOMP loader installing LONGTALE, a malicious Chrome extension disguised as Google Gemini that steals cookies, session tokens, and keystrokes. Volexity assesses with low confidence the exploit chain was sold or shared among different Chinese end-users.
China-Linked UNC3569 Exploited Sogou Input Method Flaw to Deploy GRAYRABBIT Backdoor
China-linked UNC3569 exploited a Sogou Input Method flaw to deploy GRAYRABBIT backdoor on Windows machines across East and Southeast Asia.
Gen Digital found that China-linked UNC3569, a hacker-for-hire group tracked by Google since 2021, exploited a flaw in Sogou Input Method's Windows sgbiz: link handler to reach a sandbox-disabled Chromium 80 build and exploit 2021's CVE-2021-38003 for code execution. The chain delivered GRAYRABBIT, a remote shell backdoor capable of file transfer and module loading, via a 7-Zip DLL sideloading trick gated on process count. Tencent fixed the handler flaw in April 2026 but the embedded browser remains outdated. Sogou has over 455 million monthly users and roughly 70% share of Chinese input methods.
Four Nation-State Actors Used the Same Chrome Zero-Day Exploit Kit Within 12 Days
Proofpoint reports four nation-state actors, mostly China-nexus, adopted the BlueMoon Chrome and Windows zero-day exploit kit within 12 days, targeting US organizations.
Proofpoint tracked an exploit kit dubbed BlueMoon that chains CVE-2026-85046, a Chrome V8 type-confusion bug, with an unnamed V8 sandbox escape and CVE-2026-85880, a Windows kernel privilege escalation using ALPC and the Windows Notification Facility. The first observed use was by China-nexus TA412 (APT31, Violet Typhoon, JungleBamboo) on August 28, 2026 against US NGOs, mining companies, and commodity trading firms, followed by UNK_LateNight targeting US aerospace and defense companies on September 2. Both V8 bugs were patch-gap zero-days: the fix was committed to Chromium on August 7 but reached stable Chrome on September 3, enabling rapid weaponization from public patches. TA412's post-exploitation payload, GemStone, is a malicious browser extension posing as an AI-powered Google Gemini companion that captures keystrokes, cookies, screenshots, and browsing history via a Cloudflare Worker C2.
Chinese espionage groups swarm to exploit triple-link chain of zero-days
Four China-aligned espionage groups, starting with TA412/APT31, chained zero-days CVE-2026-85046, CVE-2026-87491 and CVE-2026-85880 to spy on targets since late August.
TA412 (Violet Typhoon/APT31) began exploiting the BlueMoon chain on Aug. 28, followed by UNK_LateNight (US aerospace, Sept. 2), UNK_DoubleCheck (Vietnamese manufacturing via a compromised Southeast Asian government account) and UNK_QuietRacket (Indonesia and Singapore government, consulting and finance, Sept. 3). The chain pairs Chromium JavaScript engine RCE flaws CVE-2026-85046 and CVE-2026-87491 with the Windows ALPC privilege-escalation zero-day CVE-2026-85880, enabling sandbox escape and system privileges. Delivery used phishing links installing a fake Google Gemini browser extension that surveilled browser activity and stole credentials; Proofpoint directly observed fewer than 20 organizations but expects wider proliferation as the kit spreads.
Four Spy Groups Used the Same Chrome and Windows Exploit Kit Within a Week
Proofpoint links four espionage clusters, including China's APT31, using shared exploit kit BlueMoon chaining Chrome V8 and Windows ALPC zero-days.
Proofpoint reports a previously undocumented exploit kit, BlueMoon, chains Chrome V8 type confusion CVE-2026-85046 with an unassigned V8 sandbox escape and Windows ALPC heap overflow CVE-2026-85880 to achieve code execution and local privilege escalation. APT31 first used it on August 28, 2026 against US NGOs, mining, and commodity trading firms, deploying the GemStone browser backdoor disguised as a Google Gemini extension via the GhostChrome-X integrity bypass. UNK_LateNight, UNK_DoubleCheck, and UNK_QuietRacket followed on September 2-3, targeting US aerospace, Vietnamese manufacturing, and Indonesian/Singaporean sectors with ShadowPad and sideloaded Rust and .NET payloads. Both V8 flaws were patch-gap zero-days, and verbose code suggests possible AI-assisted development.
Google Pixel phones pwned in zero-click attacks
CISA added actively exploited zero-click Pixel modem flaw CVE-2026-58704 to its KEV catalog, giving federal agencies three days to patch.
Google disclosed CVE-2026-58704, a high-severity improper authorization flaw in Pixel phones' cellular modems that bypasses permission checks and escalates privileges with no user interaction, noting limited, targeted exploitation. CISA added it to the Known Exploited Vulnerabilities Catalog with a September 19 deadline for federal agencies. Such zero-click modem bugs are a frequent vector for commercial spyware. The Register also notes two recently KEV-listed Chromium V8 flaws, CVE-2026-85046 and CVE-2026-87491, which Proofpoint says four espionage groups chained in intrusions.