Heimdall has an authorization bypass via path normalization mismatch

Exploitation

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

CVSS 4.0

7.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N · score source

EPSS

• CVE-2026-42274: 0.37% estimated exploitation activity in the next 30 days; percentile 30.75 (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 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 allowencodedslashes option to be set to on or nodecode.) while the downstream ultimately processes a different, normalized path (/admin). Details This vulnerability can be exploited by an adversary if rule matching is performed using free (named or unnamed) wildcards without further constraints, as shown in the example snippets below. If an adversary sends a request to /public/../user/whatever, rule-2 will be matched and executed. The downstream service may, however, normalize the request path and interpret it as /user/whatever. Impact Bypass of access control policies enforced by heimdall may lead to the…

Published by the source

25 Apr 2026, 23:30 UTC

Last modified by the source

12 May 2026, 13:29 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3q34-rx83-r6mq

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# Patch Next advisory brief: CVE-2026-42274

Advisory: Heimdall has an authorization bypass via path normalization mismatch
IDs: CVE-2026-42274, GHSA-3q34-rx83-r6mq
Record: https://patchnext.com/advisories/cve-2026-42274 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/dadrus/heimdall 0.17.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/dadrus/heimdall: affected < 0.17.14; fixed in 0.17.14

## Suggested inspection (read-only)
- Go github.com/dadrus/heimdall: 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/dadrus/heimdall.
- 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-3q34-rx83-r6mq (GitHub-reviewed advisory GHSA-3q34-rx83-r6mq lists affected ranges: Go github.com/dadrus/heimdall >=0 <0.17.14)

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