Ubuntu issued USN-8740-1 fixing two .NET watch flaws, CVE-2026-58649 and CVE-2026-69806, enabling information exposure and privilege escalation.
Ubuntu Security Notice USN-8740-1 addresses two vulnerabilities in .NET watch components. CVE-2026-58649 involves missing cross-origin WebSocket validation in BrowserRefreshServer that could expose sensitive information. CVE-2026-69806 involves improper information exposure through AspireServerService arguments, potentially allowing privilege elevation and arbitrary code execution.
Canada's Cyber Centre relays Microsoft's September 2026 rollup; CISA added exploited zero-days CVE-2026-85880 and CVE-2026-81963 to KEV.
Advisory AV26-896 from the Canadian Centre for Cyber Security summarizes Microsoft's September 2026 monthly security rollup, listing affected products across Windows, Office, .NET, Azure, Exchange and SQL Server. It notes Microsoft confirmed CVE-2026-81963 and CVE-2026-85880 have been exploited. On September 8, 2026, CISA added both CVEs to its Known Exploited Vulnerabilities catalog, and administrators are urged to apply the updates.
Microsoft's September 2026 Patch Tuesday fixes a record 964 CVEs, including two zero-days actively exploited in the wild.
Microsoft patched a record 964 CVEs in its September 2026 Patch Tuesday release, with 101 rated critical and 824 rated important, making it the largest Patch Tuesday to date. The release includes fixes for two zero-days that were exploited in the wild, with CVE-2026-81963 and CVE-2026-85880 highlighted in the release. Affected products span Windows core components, Office, Exchange, .NET, Visual Studio, Active Directory services (including AD CS and AD FS) and numerous Azure services. Tenable notes the release surpasses July's as the biggest ever.
Canada's Cyber Centre updated advisory AV26-804 relaying Microsoft's August 2026 monthly rollup of vulnerabilities across .NET and Azure products.
The Canadian Centre for Cyber Security advisory AV26-804, updated August 27, 2026, relays Microsoft's August 2026 monthly security rollup originally issued August 11. Affected products include .NET 8.0, 9.0, and 10.0 on Linux, macOS, and Windows, plus many Azure services. Listed Azure components include Azure Kubernetes Service, Azure SQL Database, Azure Service Bus, Azure Active Directory, Azure Logic Apps, and Azure Monitor Agent.
Microsoft's August 2026 Patch Tuesday fixes 398 CVEs, including an actively exploited WinSock zero-day CVE-2026-68820 and wormable DNS RCE CVE-2026-62878.
Microsoft's August 2026 Patch Tuesday addresses 398 CVEs across Windows, Office, Azure, Exchange Server, SharePoint, Teams, .NET and other products, with 62 rated Critical. The actively exploited CVE-2026-68820 is a use-after-free in the Windows WinSock afd.sys driver that can yield SYSTEM privileges via a race condition. CVE-2026-62878 is a critical, wormable stack buffer overflow in Windows DNS Server allowing unauthenticated, remote code execution without user interaction. Other notable fixes include WDS TFTP RCE CVE-2026-62893, a QUIC flaw affecting roughly 13.5 million sites (CVE-2026-62815), an Exchange authentication bypass EoP demonstrated at Pwn2Own Berlin (CVE-2026-62911), and two TPM 2.0 reference implementation fixes.
Tenable reports Microsoft's August 2026 Patch Tuesday addresses 398 CVEs including three zero-days, one exploited in the wild (CVE-2026-68820).
Microsoft patched 398 CVEs in its August 2026 Patch Tuesday release, with 42 rated critical, 355 important, and one moderate, and three zero-days among them. One zero-day is confirmed as exploited in the wild. The release covers components including .NET, .NET Framework, Active Directory Certificate Services (AD CS), Azure services, and Windows. Tenable's count omits two CVEs assigned by MITRE, CVE-2026-6726 and CVE-2026-6727.
Heap-Based Buffer Overflow in Windows ALPC Enables Local Privilege Escalation
CVE-2026-85880 is a heap-based buffer overflow in Windows Advanced Local Procedure Call (ALPC), the Windows mechanism for local inter-process communication. An authorized local attacker can trigger the overflow by submitting crafted input over ALPC, corrupting heap memory in the component that handles the request. Successful exploitation allows the attacker to execute code with elevated privileges, typically gaining SYSTEM-level control of the local host, which is especially valuable as a post-exploitation or sandbox-escape step. Affected products include Windows 10 (1607, 1809, 21H2, 22H2) and Windows Server 2012, 2016, 2019, and 2022, meaning most on-premises Windows estates are in scope. The flaw was fixed in Microsoft's record 974-CVE September 2026 Patch Tuesday and was added to CISA's KEV on 2026-09-08, confirming exploitation in the wild; press reports describe Windows zero-days being chained with a Chrome zero-day in 'BlueMoon' kit attacks, though the data does not explicitly confirm this CVE is the Windows flaw in that chain.
· Microsoft Windows 10 1607, 1809, 21H2, 22H2 · Microsoft Windows Server 2012, 2016, 2019, 2022 KEVmass
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
Use-After-Free Local Privilege Escalation in Microsoft Windows WinSock AFD Driver
CVE-2026-68820 is a use-after-free (CWE-416) in the Windows Ancillary Function Driver for WinSock (afd.sys), the kernel component that handles Winsock socket operations. A local, authenticated attacker can trigger the memory corruption through crafted socket activity, and the high attack-complexity score (AV:L/AC:H/PR:L) indicates exploitation requires a specific, likely race-sensitive sequence of operations. Successful exploitation elevates privileges to SYSTEM, giving the attacker full control of the host, and public reporting describes deployment of a backdoor after privilege escalation. Virtually every Windows 10, Windows 11, and Windows Server (2012-2022) installation ships this driver, so the affected population is essentially the entire supported Windows installed base. The flaw is being exploited in the wild: CISA added it to the KEV on 2026-08-11, Microsoft fixed it in the August 2026 Patch Tuesday release, and reporting ties active exploitation to North Korea's Lazarus group, who paired the zero-day with fake job-offer lures.
· Microsoft Windows Ancillary Function Driver for WinSock (afd.sys) as shipped with the Windows versions listed below · Microsoft Windows 10 1607, 1809, 21H2, 22H2 KEVmass
Unauthenticated Stack Buffer Overflow RCE in Windows DNS (CVE-2026-62878)
Windows DNS contains a stack-based buffer overflow (CWE-121) that an unauthenticated, network-adjacent or internet-reachable attacker can trigger by sending crafted input to the DNS service. Successful exploitation yields remote code execution on the target host, with high impact on confidentiality, integrity and availability (CVSS 3.1: 9.8). The flaw affects the DNS component shipped with Windows 10 1607 and 1809 and with Windows Server 2012, 2016, 2019, 2022 and 2025; systems running the DNS Server role, especially internet-facing DNS servers and domain controllers, are the primary targets. Microsoft, which assigned the CVE, has issued a fix, and the flaw appeared amid a record-sized run of Patch Tuesday releases. No in-the-wild exploitation is currently known: it is not in CISA's KEV, no public proof-of-concept is available, and EPSS estimates only a 1.3% probability of exploitation within 30 days.
· microsoft Windows 10 1607 · microsoft Windows 10 1809mass
Use-after-free RCE in Microsoft MsQuic via crafted network packets
A use-after-free (CWE-416) in Microsoft's QUIC implementation (MsQuic) allows an unauthenticated remote attacker to execute code on an affected host. The flaw arises because creating and removing new network paths in response to incoming packets can invalidate a pointer that is subsequently used. An attacker needs only to send a specially crafted packet to a service speaking QUIC, with no authentication or user interaction required; the maximum CVSS 4.0 score of 10 (critical) reflects full system-compromise potential. Any deployment of the MsQuic library is affected, including services built on Microsoft's in-box QUIC support (e.g., HTTP/3 and SMB over QUIC) and applications consuming the public NuGet package, though exact affected version ranges are not specified in the available data. Exploitation has not been observed: there is no public proof-of-concept, the issue is not in CISA's KEV, and EPSS puts the 30-day exploitation probability at about 1 percent, but a fix ('Guard path promotion', commit e0f55b5) is already available.
· Microsoft MsQuic (Microsoft QUIC library; distributed via NuGet) · Microsoft Services and applications using MsQuic (e.g., HTTP/3, SMB over QUIC, .NET System.Net.Quic)mass
Info Leak in TCG TPM 2.0 Reference Code Enables Attestation Key Forgery
An information-leakage flaw in the Trusted Computing Group's TPM 2.0 reference code (tracked by TCG as VRT0010 and by CERT/CC as VU#431093) allows a local attacker with elevated privileges to obtain a credential from a TPM-aware certificate authority for a falsified TPM key. It is triggered locally on systems whose TPM runs code derived from the TCG reference implementation when the attacker manipulates key-attestation flows for keys such as an Attestation Key, DevID Key, or TLS authentication key. With the fraudulently issued credential, the attacker can falsify other TPM 2.0 attestations with that key, undermining device-identity and attestation guarantees. Any deployment of the TCG TPM 2.0 reference code - including commercial TPM chips, firmware TPMs, and TPM-aware CA/attestation infrastructure - is potentially affected; the available data does not specify version ranges. No exploitation has been observed: there is no public proof-of-concept, the issue is not in CISA's KEV, and EPSS estimates only a ~0.2% chance of exploitation in the next 30 days.
· Trusted Computing Group (TCG) TPM 2.0 reference code (and TPM implementations derived from it)mass
Local Privilege Escalation via Sensitive Information Exposure in Microsoft .NET
CVE-2026-69806 is an information-exposure flaw in Microsoft .NET (CWE-200, with an associated code-generation issue, CWE-94) that allows an authorized actor to elevate privileges locally. To trigger it, an attacker must already hold a low-privileged foothold on the target system — such as the ability to execute code as a standard local user — and the high-complexity local attack path requires no user interaction. A successful exploit carries high-impact confidentiality, integrity, and availability consequences, effectively yielding elevation of privilege on the affected host. Any organization running the affected .NET components on Windows clients or servers is in scope, and the fix shipped in Microsoft's September 2026 Patch Tuesday (September 8, 2026), part of a record 966-flaw release. There is no public proof-of-concept, the flaw is not in CISA KEV, and no in-the-wild exploitation is known; EPSS assigns a 1.8% probability of exploitation within 30 days (77th percentile).
· Microsoft .NET (sensitive information exposure leading to local elevation of privilege)mass
Origin Validation Error in Microsoft .NET Enables Cross-Origin Information Disclosure
CVE-2026-58649 is an origin validation error (CWE-346) in Microsoft's .NET platform, meaning the runtime fails to correctly verify the origin of network requests, allowing an unauthenticated attacker to trigger an information-disclosure condition. The CVSS vector (AV:N/AC:L/PR:N/UI:R) indicates the flaw is reachable over a network with low attack complexity and no privileges required, but a victim user must interact with attacker-influenced content for it to fire. A successful attacker gains access to confidential information handled by the affected application (confidentiality impact rated High), with no integrity or availability impact. Any organization running supported .NET deployments that have not yet received the September 2026 Patch Tuesday updates is potentially affected. There is currently no public proof-of-concept, the flaw is not in CISA's KEV, and EPSS puts 30-day exploitation probability at just 0.3%, so no in-the-wild exploitation is known.
Timing Side-Channel in TCG TPM 2.0 Reference Code RSA-OAEP Decryption
CVE-2026-6727 is a timing side-channel vulnerability (CWE-208, tracked as TCGVRT0011) in the RSA OAEP decryption implementation of TPM 2.0 code derived from the Trusted Computing Group reference implementation. A privileged local attacker with access to the TPM command interface can measure timing differences across decryption operations to recover information sufficient to decrypt ciphertexts encrypted to TPM-managed RSA keys, including the RSA Endorsement Key (EK), import blobs, credential blobs, and session salts. Under certain conditions, the leaked information may also enable forgery of TPM 2.0 attestations, undermining trust in remote-attestation results. Any platform whose TPM 2.0 firmware is built from the affected TCG reference code is potentially affected, which spans TPM silicon from multiple vendors shipped across modern PCs, laptops, and servers; per-vendor exposure depends on whether the vulnerable code path was adopted. No public proof-of-concept or known exploitation exists (EPSS 0.2% over 30 days, not in CISA KEV).
· Trusted Computing Group TPM 2.0 reference code (TCGVRT0011 / VU#431093) · TPM 2.0 implementations built from the TCG reference codemass
Local Tampering via Link-Following Flaw in Windows 11 26H1 Container Isolation Driver
CVE-2026-72971 is a link-following flaw (CWE-59) in the Windows Container Isolation FS Filter Driver (unionfs.sys) on Windows 11 26H1: the driver performs file access without fully verifying that the path is not redirected through a symbolic link or junction. A local attacker who already holds low-privilege access (CVSS AV:L/PR:L, no user interaction required) can plant a malicious link at a location the driver processes, causing it to follow the link and act on an attacker-chosen target. The attacker gains tampering capability, which the CVSS scores as High integrity impact with no confidentiality or availability impact, meaning they can modify or overwrite files their account could not normally change. Any Windows 11 26H1 system is in scope per the CVE data, with the highest practical risk on shared or multi-user hosts and machines using container isolation features where unionfs.sys is active. No active exploitation is known: the CVE is not in CISA KEV, no public proof-of-concept exists, and EPSS puts 30-day exploitation probability at about 0.5%; the related news shows Microsoft's August 2026 Patch Tuesday shipped 400+ fixes, and defenders should confirm their devices received the unionfs.sys patch.
· microsoft Windows 11 26H1 (Container Isolation FS Filter Driver, unionfs.sys)mass
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