CVE-2026-44881
CVE-2026-44881 is a security vulnerability in github.com/portainer/portainer. O3 Security confirms whether CVE-2026-44881 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Portainer: Arbitrary File Read via Git Symlink Injection in Stack Auto-Update
Real-World Exposure
github.com/portainer/portainer🐹github.com/portainer/portainer🐹github.com/portainer/portainerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Portainer Community Edition is a lightweight service delivery platform for containerized applications that can be used to manage Docker, Swarm, Kubernetes and ACI environments. From 2.33.0 to before 2.33.8, 2.39.2, and 2.41.0, Portainer supports deploying stacks from Git repositories. When a Git-backed stack is created or updated, Portainer clones the repository using go-git v5, which translates Git blob entries with mode 0o120000 (symlink) into real OS symlinks on the host filesystem via os.Symlink. The only entry blocked from becoming a symlink is .gitmodules; every other path is created as a symlink without validation. Portainer's GET /api/stacks/{id}/file endpoint then reads the stack entry point with os.ReadFile, which follows OS symlinks transparently. A repository containing docker-compose.yml as a symlink to an arbitrary filesystem path causes the symlink target's contents to be returned verbatim in the HTTP response. Any authenticated user with rights to create or update a Git-backed stack — the default configuration in Portainer CE — can read arbitrary files accessible to the Portainer process. This vulnerability is fixed in 2.33.8, 2.39.2, and 2.41.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/portainer/portainer | ≥ 2.33.0&&< 2.33.8 | 2.33.8 |
| 🐹Go | github.com/portainer/portainer | ≥ 2.39.0&&< 2.39.2 | 2.39.2 |
| 🐹Go | github.com/portainer/portainer | ≥ 2.40.0&&< 2.41.0 | 2.41.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/portainer/portainer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/portainer/portainer to 2.33.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44881 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-44881 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-44881. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-44881 in your dependencies?
O3 detects CVE-2026-44881 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.