Microsoft Patch Tuesday, September 2026 Security Update Review
Microsoft's September 2026 Patch Tuesday fixes 974 vulnerabilities, including 113 critical and two actively exploited Windows privilege escalation flaws.
Microsoft's September 2026 Patch Tuesday fixes 974 vulnerabilities, its largest release ever, including 113 critical and 860 important, covering Windows HTTP.sys, Hyper-V, Entra ID, Exchange Server, Office, DNS, and more. Two zero-days are confirmed exploited in the wild: CVE-2026-81963 (Windows Update Stack EoP) and CVE-2026-85880 (ALPC heap overflow), both letting authenticated attackers gain SYSTEM privileges. Notable criticals include an Entra ID authentication bypass (CVE-2026-62916) and multiple Windows DNS Server and Office remote code execution flaws.
CISA Adds Three Known Exploited Vulnerabilities to Catalog
CISA added three actively exploited vulnerabilities — two JFrog Artifactory and one ConnectWise ScreenConnect — to its KEV Catalog.
CISA added CVE-2026-42016 (JFrog Artifactory incorrect authorization), CVE-2026-42018 (JFrog Artifactory improper authentication), and CVE-2026-84869 (ConnectWise ScreenConnect improper privilege management and missing authorization) to the Known Exploited Vulnerabilities Catalog based on evidence of active exploitation. BOD 26-04 requires Federal Civilian Executive Branch agencies to prioritize rapid remediation of such high-risk vulnerabilities on publicly exposed assets and to check for prior compromise. CISA urges all organizations to adopt risk-based vulnerability management and prioritize KEV remediation.
U.S. CISA adds GitLab, JFrog Artifactory, and ConnectWise ScreenConnect flaws to its Known Exploited Vulnerabilities catalog
CISA added four actively exploited GitLab, JFrog Artifactory, and ConnectWise ScreenConnect flaws to the KEV catalog with imminent deadlines.
CISA added CVE-2026-42016 and CVE-2026-42018 (JFrog Artifactory), CVE-2026-84869 (ConnectWise ScreenConnect), and CVE-2026-85706 (GitLab, CVSS 10.0) to its KEV catalog. Artifactory flaws are being chained with CVE-2026-82329 in attacks observed August 15 to September 8, taking over self-hosted servers, creating persistent administrator accounts, and installing backdoors. ScreenConnect CVE-2026-84869 allows unauthorized file transfer and execution during remote sessions, linked by Huntress to malicious VBScript deliveries, and is fixed in version 26.6.5. GitLab's repository commits API path traversal exposes SSH keys, database credentials, deploy tokens, and CI/CD variables, with watchTowr already observing in-the-wild probes. Federal agencies must patch GitLab and ScreenConnect flaws by September 14, 2026, and Artifactory flaws by September 25, 2026.
CISA Adds Three Known Exploited Vulnerabilities to Catalog
CISA added three actively exploited vulnerabilities to its KEV catalog: CVE-2023-49105 (ownCloud), CVE-2026-53362 (Linux kernel), and CVE-2026-66384 (JFrog Artifactory).
CISA added three new entries to the Known Exploited Vulnerabilities catalog based on evidence of active exploitation: ownCloud improper authentication (CVE-2023-49105), an unspecified Linux kernel vulnerability (CVE-2026-53362), and JFrog Artifactory improper path restriction (CVE-2026-66384). KEV listing confirms these flaws are being exploited in the wild rather than posing theoretical risk. Under BOD 26-04, federal civilian executive branch agencies must prioritize remediation of KEV entries.
Broken access control in the RADIUS type admin group
FortiWeb RADIUS admin authentication flaw (CVSS 8.8) permits remote GUI/CLI login with random credentials under specific non-default settings.
Fortinet advisory FG-IR-26-158 describes an improper authentication flaw (CWE-287) in FortiWeb's Remote RADIUS-type admin authentication, scored CVSSv3 8.8. When the configuration uses specific non-default settings, a remote unauthenticated attacker can log into the FortiWeb GUI or CLI with a random username and password. The advisory was revised on 2026-08-12 and does not state that exploitation has been observed.
Fortinet Patches Critical Vulnerabilities in FortiMonitorOnSight, Chrome Extension
Fortinet patched 10 vulnerabilities including two critical authentication flaws, CVE-2026-84390 (CVSS 9.6) and CVE-2026-84388 (CVSS 9.1), in FortiMonitorOnSight and the FortiPAM Chrome extension.
Fortinet's September patch release fixes CVE-2026-84390, a sensitive-information issue in the FortiMonitorOnSight web portal that lets unauthenticated attackers bypass authentication with forged or reused JWTs. CVE-2026-84388 is an improper authentication flaw in the Fortinet Privileged Access Agent Chrome extension that can allow attackers to proxy a user's browser traffic via a malicious website, requiring upgrades to both FortiPAM 1.9.1/1.8.4 and extension 8.0.1.123+. High-severity information disclosure in FortiSandbox (CVE-2026-26084) and man-in-the-middle risk in the FortiOS/FortiProxy Agentless ZTNA portal (CVE-2026-84393) were also fixed, alongside medium/low issues across FortiManager, FortiAnalyzer, FortiSOAR, FortiClient, FortiSIEM and others. Fortinet did not indicate any of the flaws are being exploited in the wild.
CISA Added JFrog Artifactory Vulnerability to its Known Exploited Vulnerabilities Catalog (CVE-2026-82329)
CISA added the actively exploited JFrog Artifactory flaw CVE-2026-82329 (CVSS 9.8) to its KEV catalog; unauthenticated attackers gain admin access.
CISA added CVE-2026-82329, a critical improper authentication flaw in JFrog Artifactory, to its Known Exploited Vulnerabilities Catalog with a September 5, 2026 patch deadline. The CVSS v3.1 9.8 flaw allows unauthenticated attackers with network access to obtain administrative privileges under the default configuration. WatchTowr honeypot data shows attackers minting administrator tokens, enumerating users, groups, and federated access topologies, and in some cases creating backdoor users for persistence. Users must upgrade to Artifactory 7.161.20 or the applicable fixed release; Qualys detects vulnerable assets via QID 735249.
VU#874418: RDK-B WebUI contains multiple vulnerabilities
CERT/CC warns RDK-B WebUI rdkb-2025q4-kirkstone contains multiple flaws enabling network attackers to bypass authentication, cause DoS, or potentially execute code.
VU#874418 describes multiple vulnerabilities in the RDK-B WebUI version rdkb-2025q4-kirkstone, the open-source Reference Design Kit for Broadband used in broadband gateways and networking devices. Issues include memory corruption, improper authentication, race conditions, and insufficient input validation. A network-adjacent attacker could bypass authentication, obtain administrative access, cause denial-of-service, or corrupt underlying processes, with potential arbitrary code execution under certain conditions.
Hackers Chain Two New SonicWall Zero-Day Vulnerabilities
SonicWall warns two zero-days (CVE-2026-83548 SSRF, CVE-2026-83549 post-auth RCE) in SMA1000 appliances are being actively exploited.
A September 1 SonicWall advisory discloses actively exploited zero-days in SMA1000 appliance models 6210, 7210 and 8200v, affecting platform-hotfix versions 12.4.3-03453 and 12.5.0-02835 and older. CVE-2026-83548 (CVSS 10.0) is a pre-authentication SSRF in the Appliance Work Place interface via an unintended alternate access path; CVE-2026-83549 (CVSS 7.8) is post-authentication OS command injection enabling RCE in the Appliance Management Console. SonicWall urges hotfix upgrades, IOC checks with SonicWall support, and re-imaging plus credential and TOTP resets if compromise is found.
Microsoft Patch Tuesday for September 2026 — Snort rules and prominent vulnerabilities
Microsoft's September 2026 Patch Tuesday fixes 973 vulnerabilities, including 113 critical, with two Windows privilege-escalation bugs (CVE-2026-81963, CVE-2026-85880) exploited in the wild.
Microsoft's September 2026 security update addresses 973 vulnerabilities across its product lineup, 113 rated critical, of which 82 are remote code execution flaws. Two vulnerabilities are confirmed exploited in the wild: CVE-2026-81963, an elevation-of-privilege flaw in the Windows Update Stack (CVSS 7.8), and CVE-2026-85880, a heap-based buffer overflow in Windows Advanced Local Procedure Call (CVSS 7.8). Microsoft flags several bugs as more likely to be exploited, including a 9.8 RCE in Windows DNS Server (CVE-2026-69730), an 8.8 RCE in Windows Kerberos (CVE-2026-69676), and a 9.0 EoP in Spring Cloud Azure (CVE-2026-69854). Cisco Talos published accompanying Snort rules to detect exploitation attempts against the prominent flaws.
ThreatsDay: CEO Phishing Kits, 5K Dropbox Account Hacks, OAuth Traps + 17 More Stories
Microsoft warns of Teams IT-impersonation intrusions deploying Node.js implants; Spring Ring vishing hit 150+ employees across 10 companies; The Gentlemen ransomware claims 683 victims.
Microsoft warned of a human-operated campaign abusing Teams external collaboration to impersonate IT help desk staff, deploy malicious MSI packages staging Node.js runtimes and obfuscated JavaScript implants, then pivot to domain controllers over WinRM. Unit 42 documented the Spring Ring vishing operation targeting over 150 employees across at least 10 companies using 26 attacker identities, including an NTLM relay variant against domain controllers. Sophos reported The Gentlemen ransomware (Gold Sherwood) reached 683 total victims by end of July 2026, adding 169 in July, with a playbook using BYOVD-based EDR killers and backup tampering. Group-IB found the Outsider phishing-as-a-service platform created 700+ new phishing pages within a month despite law enforcement takedowns.