Vulnerability in github.com/dadrus/heimdall (CVE-2026-42274)
Summary
Vulnerability in github.com/dadrus/heimdall (CVE-2026-42274). Risk of unauthorized operations or information disclosure. Exploitable via allow_encoded_slashes. Mitigation: upgrade to 0.17.14 or later.
Original description
The description as published by the source.
Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall performs rule matching on the raw (non-normalized) request path, while downstream components may normalize dot-segments according to RFC 3986, Section 6.2.2.3. This discrepancy can result in heimdall authorizing a request for one path (e.g., /user/../admin, or URL-encoded variants such as /user/%2e%2e/admin or /user/%2e%2e%2fadmin. The latter would require the allow_encoded_slashes option to be set to on or no_decode.) while the downstream ultimately processes a different, normalized path (/admin). This issue has been patched in version 0.17.14.
Source: NIST National Vulnerability Database 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-2026-42274 has been found in github.com/dadrus/heimdall.
Attackers can target a specific entry point like allow_encoded_slashes over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade github.com/dadrus/heimdall to 0.17.14 or later.
If unsure, ask your IT team or search "github.com/dadrus/heimdall CVE-2026-42274" on the vendor's site.
CVE-2026-42274 (github.com/dadrus/heimdall) — CWE-35
Attack surface: allow_encoded_slashes / no_decode / normalize_path
Patched: 0.17.14 — 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-35) exists in github.com/dadrus/heimdall. Attackers reach the vulnerable code path via allow_encoded_slashes.
Check the vendor advisory for the affected versions of github.com/dadrus/heimdall. Attack surface: allow_encoded_slashes / no_decode / normalize_path.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 0.17.14.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/dadrus/heimdall' . 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
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1Identify exposure identify
grep -r 'github.com/dadrus/heimdall' . | 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/dadrus/heimdallを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/dadrus/heimdall to 0.17.14ステージング環境で 0.17.14 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を含めること。
-
3Post-deployment verification verify
Confirm patched version is live in production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。本番ではアクセスログ・WAF 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
- patch github.com
- patch github.com
- web github.com
- web envoyproxy.io
- web rfc-editor.org
- web github.com