EUVD-2026-322956

fkie_cve-2026-44885

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, Portainer's backup restore feature accepts a .tar.gz archive and extracts it to a target directory on the server. The extraction function (ExtractTarGz in api/archive/targz.go) constructed output paths using filepath.Clean(filepath.Join(outputDirPath, header.Name)). This combination does not prevent directory traversal — a tar entry named ../../etc/cron.d/evil resolves to a path outside the extraction root, so a crafted archive can write files to arbitrary locations on the server filesystem. This vulnerability is fixed in 2.33.8.

GHSA-m8fg-67j7-cx4v — Portainer has a path traversal in backup archive extraction that allows arbitrary file write

Affected: Go: github.com/portainer/portainer

### Summary Portainer's backup restore feature accepts a `.tar.gz` archive and extracts it to a target directory on the server. The extraction function (`ExtractTarGz` in `api/archive/targz.go`) constructed output paths using `filepath.Clean(filepath.Join(outputDirPath, header.Name))`. This combination does not prevent directory traversal — a tar entry named `../../etc/cron.d/evil` resolves to a path outside the extraction root, so a crafted archive can write files to arbitrary locations on the server filesystem.

## Severity

**Medium**

**CWE-22** — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Exploitation requires administrator access to Portainer's backup restore endpoint. An administrator who is deceived into restoring a malicious archive, or whose credentials are compromised, can use this path to write files outside the Portainer data directory.

## Affected Versions

The vulnerability exists in every Portainer release prior to 2.39.0 — `ExtractTarGz` has used `filepath.Clean(filepath.Join())` since it was introduced. The fix shipped with 2.39.0 (patched on `develop` before the 2.39 branch cut); 2.34.x–2.38.x STS releases are also affected but are end-of-life and will not receive a fix.

| Branch | First vulnerable | Fixed in | |--------------|------------------|------------| | 2.33.x (LTS) | 2.33.0 | **2.33.8** |

Portainer 2.39.0 and later are not affected — the fix was present from the initial 2.39.0 release. All…

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EUVD-2026-322956

fkie_cve-2026-44885

GHSA-m8fg-67j7-cx4v — Portainer has a path traversal in backup archive extraction that allows arbitrary file write