Attackers are actively exploiting critical SharePoint authentication bypass CVE-2026-55040 (CVSS 9.1) days after Rapid7 released a public PoC.
CVE-2026-55040 is a critical authentication bypass (CVSS 9.1) in SharePoint Server Subscription Edition that lets unauthenticated attackers forge JWT tokens and impersonate any user, including administrators. Microsoft patched it in July 2026 Patch Tuesday, but Rapid7 published a technical write-up and Python PoC on GitHub on August 12, and Defused quickly observed attackers running the PoC against SharePoint honeypots. KEVIntel recorded 12 exploitation attempts since July 19, with eight occurring on August 12-13 from IP addresses in Hong Kong, Japan, the Netherlands, Taiwan and the U.S. Admin-level SharePoint access exposes documents and data modification and can serve as a foothold into broader Microsoft 365 infrastructure; unpatched instances should apply the July update immediately.
Attackers use Rapid7's public PoC to exploit CVE-2026-55040, a critical SharePoint authentication bypass patched in July 2026.
Rapid7 researcher Stephen Fewer published technical analysis and PoC exploit code for CVE-2026-55040, an authentication bypass in SharePoint caused by flaws in the JWT token validation pipeline. Threat intelligence firm Defused observed attackers using the PoC against SharePoint honeypots, though Microsoft has not yet confirmed in-the-wild exploitation. Chained with CVE-2026-63520, the flaw can yield unauthenticated remote code execution, per NHS England Digital. CISA is urging administrators to harden SharePoint deployments by limiting direct internet exposure and using Layer 7 reverse proxies.
An Omdia survey of 500 security leaders commissioned by Rapid7 reports 97% positive AI outcomes in the SOC despite heightened executive concerns.
Omdia, commissioned by Rapid7, surveyed 500 security professionals and found 97% reporting positive outcomes from AI in security operations. 98% said AI reduces alert fatigue and 95% said it helps address staffing shortages. Despite this consensus, the report highlights a growing confidence gap and elevated concerns among security executives about where operations are headed.
Microsoft's August 2026 Patch Tuesday fixes 400+ vulnerabilities, including an actively exploited Windows zero-day (CVE-2026-68820) used by North Korean attackers.
Microsoft's August 2026 Patch Tuesday fixes over 400 vulnerabilities, including CVE-2026-68820, a use-after-free in the Windows Ancillary Function Driver exploited in the wild by North Korean actors deploying a kernel-mode rootkit in Operation Dream Job. Critical unauthenticated remote code execution flaws in Microsoft QUIC (CVE-2026-62815) and Windows DNS (CVE-2026-62878) were also patched, alongside a SharePoint RCE chain combining CVE-2026-63520 with CVE-2026-55040. Researcher Nightmare-Eclipse released ShieldBreak, a PoC bypassing the July RoguePlanet Microsoft Defender patch (CVE-2026-50656), confirmed working by Will Dormann on Windows 11.
Microsoft's August Patch Tuesday fixes 398 CVEs, including actively exploited Windows zero-day CVE-2026-68820 used by Lazarus for SYSTEM privilege escalation.
Microsoft's August 2026 Patch Tuesday release addresses 398 new vulnerabilities, 62 rated Critical by the Zero Day Initiative, with CVE-2026-68820 (CVSS 7.0), a use-after-free in the afd.sys Windows kernel driver, the only flaw flagged as actively exploited. Check Point Research attributed exploitation of the privilege escalation bug to Lazarus' Operation Dream Job campaign. Four unauthenticated remote code execution flaws rated 9.8 affect Windows DNS Server (CVE-2026-62878, called wormable by ZDI), Windows Deployment Services (CVE-2026-62893), Microsoft QUIC (CVE-2026-62815) and HPC Pack (CVE-2026-59124). The release also completes a two-part SharePoint fix with RCE component CVE-2026-63520, following July's authentication bypass fix CVE-2026-55040.
Authentication Bypass in Microsoft SharePoint Server
Microsoft SharePoint Server is affected by a weak authentication vulnerability (CWE-1390) that allows an unauthorized attacker to bypass a security feature over a network. Per the CVSS vector, exploitation requires no privileges and no user interaction with low attack complexity, so any unauthenticated attacker with network access to a vulnerable server can trigger it remotely. Impact to confidentiality and integrity is rated high (CVSS 9.1, critical), meaning the bypass effectively grants the attacker access that authentication should have prevented, with no direct availability impact. All organizations running on-premises Microsoft SharePoint Server are potentially affected; the source data does not specify affected version ranges or fixed builds, so defenders should consult Microsoft's advisory for those details. The flaw is under active exploitation: a public proof-of-concept is available on GitHub, attackers began exploiting it after the PoC went public, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-18 (EPSS ~40%, 99th percentile; ransomware association unknown).
Unauthenticated RCE in Microsoft SharePoint Server
CVE-2026-63520 is an improper input validation flaw (CWE-20) in Microsoft Office SharePoint, affecting on-premises SharePoint Server deployments. A remote, unauthenticated attacker can trigger the flaw by sending improperly validated input to the SharePoint service over the network; the high attack complexity (AC:H) indicates exploitation depends on specific conditions, but no privileges or user interaction are required. Successful exploitation results in arbitrary code execution on the server, with high impact to confidentiality, integrity, and availability — effectively full compromise of the SharePoint host. Organizations running self-hosted SharePoint Server are in scope; SharePoint Online/Microsoft 365 is not listed in the affected products. The issue is patched as of Microsoft's Patch Tuesday (headlines mark it FIXED), with Rapid7 analysis and a researcher-disclosed exploit chain available, but there is no public PoC, no CISA KEV listing, and no confirmed in-the-wild exploitation; EPSS puts exploitation probability at 2.9% (86th percentile).
· Microsoft SharePoint Server (Office SharePoint, on-premises)mass
Pre-Authentication SSRF in SonicWall SMA1000 Appliance Workplace Interface
CVE-2026-83548 is a critical (CVSS 3.1 score 10.0) server-side request forgery (SSRF) vulnerability in the Workplace interface of SonicWall SMA1000 appliances, caused by an unintended alternate access path (unprotected alternate channel, CWE-441; SSRF, CWE-918). Because it is pre-authentication, any remote unauthenticated attacker who can reach the interface can trigger it and gain unauthorized access to sensitive functionality and perform unauthorized operations. CISA lists all SonicWall SMA1000 appliances as affected, with CPE data naming the SMA 8200v and SMA 6210/7210 firmware; internet-exposed units are at highest risk. The flaw is being actively exploited in the wild: it was added to CISA's Known Exploited Vulnerabilities catalog on 2026-09-02 alongside companion zero-day CVE-2026-83549, which reporting suggests may form an attack chain with this SSRF. Exploitation probability is elevated (EPSS 4.7%, 91st percentile) and no public proof-of-concept is known.
Unsafe Reflection RCE in PaperCut NG/MF, Chained with Auth Bypass in Attacks
CVE-2026-82078 is an unsafe dynamic class loading flaw (unsafe reflection, CWE-470) in the database connection utilities of PaperCut NG and PaperCut MF: the software instantiates a database driver class based on a configurable driver name without validating it against an allowlist of approved drivers. An attacker who can manipulate system configuration parameters can point that setting at classes of their choosing, causing the server to execute arbitrary Java bytecode residing on the application classpath in the security context of the PaperCut server process. On its own the issue is rated 9.4 (Critical) with high privileges required, but when chained with the companion authentication bypass CVE-2026-81578 it yields unauthenticated remote code execution on the print-management server. All PaperCut NG and MF deployments are in scope; affected version ranges were not specified in the available data, so administrators should consult PaperCut's advisory for fixed versions. The flaw is confirmed exploited in the wild as a zero-day: it was added to CISA's KEV catalog on 2026-08-31, and public reporting describes an AI-orchestrated campaign that compromised PaperCut servers at roughly 395 organizations (~440 servers), with EPSS currently at 1.7% (76th percentile).
Remote Authentication Bypass in Citrix NetScaler ADC and NetScaler Gateway
Citrix NetScaler ADC and NetScaler Gateway contain an authentication-bypass vulnerability (CWE-288, 'using an alternate path or channel') that an unauthenticated remote threat actor can exploit. The flaw is triggerable when the appliance is configured as an AAA virtual server or as a Gateway, including SSL VPN, ICA Proxy, CVPN, or RDP Proxy deployments, allowing the attacker to bypass authentication without valid credentials. A successful bypass could give an attacker access to VPN-protected or AAA-gated resources as an authenticated user; no CVSS score has been published yet. Organizations running affected NetScaler appliances in these configurations are exposed, and affected version ranges are not specified in the available data, so defenders should consult Citrix advisory AL26-019. The flaw was added to CISA's KEV on 2026-09-09, indicating exploitation in the wild; ransomware use is unknown, no public PoC is known, and EPSS assigns a 3.4% probability of exploitation within 30 days (88th percentile).
· Citrix NetScaler ADC and NetScaler Gateway KEV PoC large
Missing Authentication for Critical Function in PaperCut NG/MF Web Interface
CVE-2026-81578 is an improper access control flaw (CWE-305) in the web management interface of PaperCut MF and PaperCut NG in which administrative requests from unauthenticated remote users trigger backend actions before access validation completes. An attacker can invoke administrative functions without logging in, allowing modification of certain system configurations. When chained with CVE-2026-82078 (unsafe dynamic class loading), the flaw has been used to achieve unauthenticated code execution. Any organization running PaperCut NG/MF, particularly servers whose web management interface is reachable from the internet or untrusted networks, is affected. The vulnerability was added to CISA KEV on 2026-08-31 and is being exploited in the wild as part of an AI-orchestrated campaign that compromised roughly 395–440 organizations.
Authenticated OS Command Injection RCE in SonicWall SMA1000 Appliance Console
CVE-2026-83549 is a post-authentication OS command injection flaw (CWE-78) in the Appliance Management Console (AMC) of SonicWall SMA1000 appliances. An attacker who authenticates to the AMC with administrator privileges can, under specific conditions, inject arbitrary operating system commands and achieve remote code execution on the appliance. Only organizations running SMA1000-series appliances, including the SMA 6210, SMA 7210, and SMA 8200v models cited in the data, are affected. CISA added the flaw to the KEV catalog on 2026-09-02, and news reports describe active exploitation, possibly chained with companion zero-day CVE-2026-83548, with reverse shells and cryptocurrency miners observed; no public proof-of-concept is known. EPSS assigns an 8.5% probability of exploitation within 30 days (95th percentile).
· SonicWall SMA1000 series appliances - Appliance Management Console (AMC) · SonicWall SMA 6210 (SMA1000 series firmware) KEVmoderate
Local Privilege Escalation via Link Following in Windows Update Stack
CVE-2026-81963 is a link-following flaw (CWE-59, improper link resolution before file access) in the Microsoft Windows Update Stack, in which the component fails to correctly resolve file links before opening them. A local attacker with low privileges can plant or manipulate a link (symlink/junction) that the privileged update stack follows during operation, redirecting its file access to an attacker-controlled target. The result is local privilege escalation — CVSS 3.1 rates this 7.8 (high) with high confidentiality, integrity, and availability impact — allowing an authorized local user or malware already on the machine to gain elevated rights. Affected products are Windows 11 23H2, 24H2, 25H2, and 26H1 and Windows Server 2025; any unpatched system on those versions is exposed to any local account holder. The flaw was fixed in Microsoft's record September 2026 Patch Tuesday (974 CVEs), was added to CISA's KEV on 2026-09-08 as one of two Windows zero-days reported as exploited in the wild, and has no known public PoC or confirmed ransomware use.
· Microsoft Windows 11 23H2, 24H2, 25H2, 26H1 · Microsoft Windows Server 2025 KEVmass
Authentication bypass in N-able N-central internal APIs before 2026.3 HF 3
CVE-2026-86207 is an authentication bypass (CWE-305) in N-able's N-central remote monitoring and management (RMM) platform that allows unauthorized access to APIs that are supposed to be internal-only. It is triggered over the network by sending requests to these internal API endpoints under specific conditions (the CVSS vector indicates some attack prerequisites and a low-privilege foothold are required). An attacker who exploits it gains highly privileged access to the N-central server's data and functions, with high impact on confidentiality, integrity and availability of the server itself. Organizations running any N-central release before version 2026.3 Hotfix 3 are affected — primarily managed service providers hosting N-central for their own operations. There is no public proof of concept, the flaw is not in CISA's KEV catalog, and EPSS puts 30-day exploitation risk at just 0.7%; note that the recent news headlines about actively exploited 'unauthenticated RCE' flaws in N-central describe separate vulnerabilities in the same product, which is why multiple hotfixes have shipped in quick succession.
· N-able N-central all versions before 2026.3 HF 3 (Hotfix 3)moderate
Race condition in Google Chrome V8 allows sandboxed code execution via crafted web page
CVE-2026-85045 is a race condition (CWE-367, a time-of-check-to-time-of-use flaw) in the V8 JavaScript engine used by Google Chrome. An attacker triggers it by persuading a user to open a specially crafted HTML page, in which a timing window during V8's handling of an object leaves stale state that the attacker can leverage. Successful exploitation lets a remote attacker execute arbitrary code inside Chrome's renderer sandbox (but not escape it), yielding code execution at the browser's sandboxed privilege level; CVSS 3.1 rates this 7.5 High with a network vector, high attack complexity, and required user interaction. All Google Chrome installations running versions prior to 152.0.7977.82 are affected, which given Chrome's ubiquity means effectively every unpatched desktop and mobile Chrome deployment worldwide. No public proof-of-concept is known, the flaw is not on the CISA KEV catalog, and EPSS estimates a ~0.2% chance of exploitation within 30 days, though related reporting describes a sibling Chrome zero-day (CVE-2026-85046) exploited in the wild, signaling active attacker interest in this V8 code.
· google chrome all versions prior to 152.0.7977.82mass
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