# CVE-2026-42274: Heimdall: Authorization bypass via path normalization mismatch

> Attackers can bypass authorization checks by exploiting path normalization mismatches between the proxy and downstream services, gaining unauthorized access to protected resources.

- **Severity:** High 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 May 2026
- **Updated:** 11 May 2026
- **Also known as:** GHSA-3q34-rx83-r6mq, GO-2026-5097

## What is CVE-2026-42274?

CVE-2026-42274 is a high-severity authentication bypass vulnerability in dadrus heimdall, published on 8 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-436 (Interpretation Conflict), CWE-35 (Path Traversal: '.../...//')

## Which versions are affected by CVE-2026-42274?

3 open source packages ship an affected version, including github.com/dadrus/heimdall.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/dadrus/heimdall` | Go | All versions | 0.17.14 |
| `github.com/dadrus/heimdall` | Go | All versions | 0.17.14 |
| `github.com/dadrus/heimdall` | Go | All versions | 0.17.14 |

## How do I fix CVE-2026-42274?

Upgrade github.com/dadrus/heimdall to 0.17.14 or later.

## Is CVE-2026-42274 being exploited?

There is no known exploitation of CVE-2026-42274 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42274 and fix it if it is affected.

What it is: CVE-2026-42274 is a high-severity authentication bypass vulnerability in dadrus heimdall, published on 8 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-42274 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/dadrus/heimdall (Go): affected all versions; fixed in 0.17.14
- github.com/dadrus/heimdall (Go): affected all versions; fixed in 0.17.14
- github.com/dadrus/heimdall (Go): affected all versions; fixed in 0.17.14

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-42274/ (Markdown: https://insights.sbomify.com/CVE-2026-42274/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42274
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42274
- OSV: https://osv.dev/vulnerability/CVE-2026-42274

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42274/
Summaries are generated and may contain mistakes; the official description above is the record.