Vulnerability in github.com/portainer/portainer (CVE-2026-44884)
Summary
Vulnerability in github.com/portainer/portainer (CVE-2026-44884). Confidential information can be exposed externally. Exploitable via GET /api/custom_templates/{id}/file. Mitigation: upgrade to 2.39.1 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 and 2.39.1, a missing authorization vulnerability in the Custom Template file endpoint (GET /api/custom_templates/{id}/file) allows any authenticated user to read the file content of any custom template by enumerating sequential integer IDs, bypassing Resource Control access restrictions. Template files may contain environment-specific values such as connection strings, API tokens, or registry credentials that administrators would not expect standard users to read. This vulnerability is fixed in 2.33.8 and 2.39.1.
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-2026-44884 has been found in github.com/portainer/portainer.
Attackers can target a specific entry point like GET /api/custom_templates/{id}/file over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.5/10.
What to do: upgrade github.com/portainer/portainer to 2.39.1 or later.
If unsure, ask your IT team or search "github.com/portainer/portainer CVE-2026-44884" on the vendor's site.
CVE-2026-44884 (github.com/portainer/portainer) — CWE-862 / CVSS v3 6.5
Attack vector: remote (network-reachable) / no user interaction
Attack surface: GET /api/custom_templates/{id}/file / customTemplateFile / develop
Patched: 2.39.1 — 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.
A vulnerability (CWE-862) exists in github.com/portainer/portainer. Attackers reach the vulnerable code path via GET /api/custom_templates/{id}/file.
Check the vendor advisory for the affected versions of github.com/portainer/portainer. Attack surface: GET /api/custom_templates/{id}/file / customTemplateFile / develop.
Severity: Medium (CVSS 6.5/10). Confidential information can be exposed externally.
Update to 2.39.1.
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/custom_templates/{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/custom_templates/{id}/file' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
GET /api/custom_templates/{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 2.39.1ステージング環境で 2.39.1 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/custom_templates/{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