Portainer Has an Arbitrary File Read via Git Symlink Injection in Stack Auto-Update

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.5 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-44881: 0.51% estimated exploitation activity in the next 30 days; percentile 43.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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 — including docker-compose.yml, which Portainer treats as the stack entry point — 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 (for example /etc/passwd or a mounted Kubernetes service account token) 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…

Published by the source

14 May 2026, 16:23 UTC

Last modified by the source

9 Jun 2026, 10:25 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rpgq-m5fp-32wr

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# Patch Next advisory brief: CVE-2026-44881

Advisory: Portainer Has an Arbitrary File Read via Git Symlink Injection in Stack Auto-Update
IDs: CVE-2026-44881, GHSA-rpgq-m5fp-32wr
Record: https://patchnext.com/advisories/cve-2026-44881 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/portainer/portainer 2.41.0, 2.39.2, 2.33.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/portainer/portainer: affected >= 2.33.0, < 2.33.8; >= 2.39.0, < 2.39.2; >= 2.40.0, < 2.41.0; fixed in 2.39.2, 2.33.8, 2.41.0

## Suggested inspection (read-only)
- Go github.com/portainer/portainer: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/portainer/portainer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rpgq-m5fp-32wr (GitHub-reviewed advisory GHSA-rpgq-m5fp-32wr lists affected ranges: Go github.com/portainer/portainer >=2.33.0 =2.39.0 =2.40.0 <2.41.0)

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