Is CVE-2026-42274 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-42274 being exploited in the wild.

How severe is CVE-2026-42274?

High severity, with a CVSS score of 4, published 8 May 2026.

Which products and versions are affected?

Dadrus Heimdall < 0.17.14; github.com/dadrus/heimdall (Go) < 0.17.14, SEMVER:introduced=0,fixed=0.17.14.

Is there a fix for CVE-2026-42274?

Yes. github.com/dadrus/heimdall (Go): upgrade to 0.17.14 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-42274 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-42274?

Check whether you run Dadrus Heimdall or github.com/dadrus/heimdall (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-42274: dadrus Heimdall authorization bypass via path normalization mismatch

Q: Which products and versions are affected?

Dadrus Heimdall < 0.17.14; github.com/dadrus/heimdall (Go) < 0.17.14, SEMVER:introduced=0,fixed=0.17.14.

Q: Is there a fix for CVE-2026-42274?

Yes. github.com/dadrus/heimdall (Go): upgrade to 0.17.14 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-42274 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-42274?

Check whether you run Dadrus Heimdall or github.com/dadrus/heimdall (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-42274 · Severity: high · CVSS 4 · Published 2026-05-08

Heimdall, an identity and access proxy, is vulnerable to an authorization bypass. An attacker can use specially crafted web addresses containing relative path sequences (like /../) to trick the system into applying security rules for a public area to a restricted area. This could allow unauthorized users to access sensitive data or perform administrative actions without proper authentication.

Technologies: Dadrus Heimdall, github.com/dadrus/heimdall (Go). Vendors: Dadrus, Go.

Quick answers

Is CVE-2026-42274 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-42274 being exploited in the wild.
How severe is CVE-2026-42274?: High severity, with a CVSS score of 4, published 8 May 2026.
Which products and versions are affected?: Dadrus Heimdall < 0.17.14; github.com/dadrus/heimdall (Go) < 0.17.14, SEMVER:introduced=0,fixed=0.17.14.
Is there a fix for CVE-2026-42274?: Yes. github.com/dadrus/heimdall (Go): upgrade to 0.17.14 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-42274 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-42274?: Check whether you run Dadrus Heimdall or github.com/dadrus/heimdall (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

github.com/dadrus/heimdall (Go): upgrade to 0.17.14 or later
```
go get github.com/dadrus/heimdall@v0.17.14
```

Technical details

Heimdall performs rule matching on raw, non-normalized request paths, while downstream components may normalize dot-segments (RFC 3986). An attacker can exploit this by using path traversal sequences (e.g., /public/../admin) to match a permissive rule in Heimdall while the downstream service resolves the path to a restricted resource. This is particularly effective when Heimdall is configured with wildcard routes. The vulnerability is addressed in version 0.17.14. Workarounds include enforcing path normalization at the ingress/proxy layer (e.g., using Envoy's normalize_path) or validating rule IDs within issued JWTs.

Affected products

dadrus Heimdall < 0.17.14

Identifiers

CVE-2026-42274
GHSA-3q34-rx83-r6mq
GO-2026-5097

Timeline

2026-04-21: disclosed: Advisory published by dadrus
2026-04-25: advisory: GitHub Advisory published
2026-04-25: patched: Fix released in version 0.17.14

References

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