Information Disclosure in github.com/portainer/portainer (CVE-2026-44881)
Summary
Vulnerability in github.com/portainer/portainer (CVE-2026-44881). Successful exploitation can lead to full system takeover. Exploitable via GET /api/stacks/{id}/file. Mitigation: upgrade to 2.41.0 or later.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-44881 has been found in github.com/portainer/portainer.
Attackers can target a specific entry point like GET /api/stacks/{id}/file over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.9/10.
What to do: upgrade github.com/portainer/portainer to 2.41.0 or later.
If unsure, ask your IT team or search "github.com/portainer/portainer CVE-2026-44881" on the vendor's site.
CVE-2026-44881 (github.com/portainer/portainer) — CWE-200 / CVSS v3 9.9
Attack vector: remote (network-reachable) / no user interaction
Attack surface: GET /api/stacks/{id}/file / os.Symlink / os.ReadFile / ChrootHelper.Symlink
Patched: 2.41.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Information disclosure (CWE-200) exists in github.com/portainer/portainer. Attackers reach the vulnerable code path via GET /api/stacks/{id}/file.
Check the vendor advisory for the affected versions of github.com/portainer/portainer. Attack surface: GET /api/stacks/{id}/file / os.Symlink / os.ReadFile / ChrootHelper.Symlink.
Severity: Critical (CVSS 9.9/10). Successful exploitation can lead to full system takeover.
Update to 2.41.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual GET /api/stacks/{id}/file requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/portainer/portainer' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/portainer/portainer' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/portainer/portainerを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'GET /api/stacks/{id}/file' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
GET /api/stacks/{id}/fileへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade github.com/portainer/portainer to 2.41.0ステージング環境で 2.41.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against GET /api/stacks/{id}/file on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com