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.
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 read arbitrary files accessible to the Portainer process.
The issue is amplified by Git-stack auto-update: an attacker can create a stack from a legitimate repository, pass initial review, and later push a commit that replaces docker-compose.yml with a symlink; the file read is then triggered on the next scheduled update cycle with no further interaction required.
Severity
High
Attack complexity is Low: the attacker needs only the ability to host a Git repository…
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 nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com