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Microsoft security advisory – September 2026 monthly rollup (AV26-896) – Update 1
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.
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Threat Brief: OWASSRF Vulnerability Exploitation
Unit 42 details active exploitation of Exchange SSRF flaws CVE-2022-41080/CVE-2022-41082 via the OWASSRF method, deploying the SilverArrow PowerShell backdoor.
Unit 42 documents OWASSRF, an exploit chain combining CVE-2022-41080 and CVE-2022-41082 to achieve remote code execution on Microsoft Exchange via Outlook Web Access, bypassing Microsoft's ProxyNotShell mitigations. Active exploitation was observed in late November and early December 2022, affecting at least eight organizations. Attackers authenticated to Exchange, then executed a PowerShell backdoor tracked as SilverArrow to create admin accounts, install AnyDesk, tunnel RDP via PuTTY Link, and dump LSASS memory for credential theft. Exploitation is isolated rather than mass-scale because authentication is required.
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AWS Systems Manager Agent Vulnerability Allows Attackers to Bypass Port-Forwarding Restrictions
Critical SSRF flaw in AWS SSM Agent (CVE-2026-89049) lets authenticated users bypass link-local denylists and reach EC2 Instance Metadata Service for IAM credentials.
CVE-2026-89049 (Critical, CVSS v3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H) affects Amazon SSM Agent versions earlier than 3.3.4851.0, with the fix shipping in 3.3.4851.0. The remote-host port-forwarding feature's denylist for link-local addresses can be bypassed because equivalent address representations are not validated, enabling SSRF to restricted endpoints such as the EC2 Instance Metadata Service at 169.254.169.254. An attacker with authenticated AWS access and ssm:StartSession permission could retrieve instance profile IAM credentials and pivot to S3, Secrets Manager, Lambda, or other cloud resources depending on role permissions.
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Docker Sandboxes Vulnerabilities Let Malicious Guests Escape Workspace and Access Host Files
Docker fixed two symlink-race flaws in Docker Sandboxes, CVE-2026-77179 and CVE-2026-79994, letting malicious guests escape the workspace and read host files; fixed in 0.42.0.
Docker patched CVE-2026-77179 (Critical) and CVE-2026-79994 (High) in Docker Sandboxes 0.42.0, released September 7. Both are time-of-check-to-time-of-use symlink races: CVE-2026-77179 in the macOS virtio-fs host server (versions 0.28.0 to before 0.42.0) can allow a malicious guest to read or modify arbitrary host files and potentially achieve code execution, while CVE-2026-79994 in the guest-to-host Unix socket relay (0.37.0 to before 0.42.0) can redirect host connections to arbitrary AF_UNIX sockets. Docker recommends upgrading and, as interim mitigation, using clone mode and avoiding read-write host mounts.
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