Portainer has a path traversal in backup archive extraction that allows arbitrary file write

Exploitation

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

CVSS

5.5 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:L

EPSS

• CVE-2026-44885: 0.61% estimated exploitation activity in the next 30 days; percentile 49.05 (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'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…

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-m8fg-67j7-cx4v

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# Patch Next advisory brief: CVE-2026-44885

Advisory: Portainer has a path traversal in backup archive extraction that allows arbitrary file write
IDs: CVE-2026-44885, GHSA-m8fg-67j7-cx4v
Record: https://patchnext.com/advisories/cve-2026-44885 (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: Medium (CVSS 5.5)
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 2.33.8. A vendor fix does not mean a deployment is fixed.

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

## 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-m8fg-67j7-cx4v (GitHub-reviewed advisory GHSA-m8fg-67j7-cx4v lists affected ranges: Go github.com/portainer/portainer >=2.33.0 <2.33.8)

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