Last updated: September 29, 2026 at 8:42 AM UTC
All 891 Vulnerability 357 Breach 144 Threat 383 Defense 7
Tag: self-hosted (12 articles)Clear

Gitea Docker images trusted a forged header, letting anyone log in as any user

Attackers have started probing a critical flaw in Gitea's official Docker images, the self-hosted Git service used by many development teams. The images shipped a configuration that trusted the X-WEBAUTH-USER header from any source address, so with reverse-proxy login enabled, anyone who could reach the port could send that header and be authenticated as any user, no password required. Tracked as CVE-2026-20896 and rated 9.8, it was fixed in version 1.26.3 late last month, which removes the wildcard and makes reverse-proxy authentication opt-in. Sysdig reported the first exploitation attempt 13 days after disclosure, so far just reconnaissance, against some of the roughly 6,200 internet-facing Gitea instances.

Check
Check whether you run Gitea from its Docker image and on what version, review the app.ini reverse-proxy trusted-proxies setting for a wildcard, and whether the instance is internet-reachable.
Affected
Self-hosted Gitea Docker deployments on version 1.26.2 or earlier with reverse-proxy login enabled (CVE-2026-20896); an unauthenticated attacker who can reach the service can impersonate any user by forging one header.
Fix
Update Gitea to 1.26.3 or later, remove the wildcard from the reverse-proxy trusted-proxies setting, keep management interfaces off the public internet, and review logs for spoofed X-WEBAUTH-USER authentication attempts.

Critical GitHub flaw lets a single 'git push' run code remotely on the server - patched, but most self-hosted GitHub Enterprise instances haven't updated yet (CVE-2026-3854)

Researchers disclosed CVE-2026-3854, a critical GitHub Enterprise Server flaw that lets anyone with push access execute arbitrary commands on the GitHub server with a single git push. The bug is in how Enterprise Server handles repository hooks during push operations - a crafted commit message or filename bypasses the sanitization that normally prevents shell injection. GitHub patched it last week, but self-hosted instances need to apply the patch manually, and telemetry shows most haven't yet. Anyone with developer-level access to a vulnerable Enterprise Server can take over the entire instance, then pivot into every repository and CI/CD secret it hosts.

Check
If you run a self-hosted GitHub Enterprise Server, apply the latest patch this week and review push activity from any low-privilege accounts since the patch was released.
Affected
Self-hosted GitHub Enterprise Server instances on versions before the April 2026 patch. The bug requires push access to any repository, which means every developer with commit rights is a potential entry point. CI/CD secrets, signing keys, and source code are exposed. GitHub.com (the SaaS product) is not affected.
Fix
Upgrade GitHub Enterprise Server to the patched release per GitHub's advisory. Until patched, restrict push access to trusted accounts and require code review on all pushes. Audit Enterprise Server logs for unusual git operations or shell processes spawning from the GitHub system user. Rotate any CI/CD secrets, signing keys, and webhook tokens stored on the server.