# Traefik IngressRouteTCP authorization bypass in serversTransport references

Source: https://junglewise.ai/threats/traefik-ingressroutetcp-authorization-bypass-in-serverstransport-f9ba5cbc  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-22. Updated: 2026-08-05  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 5.3 · Published 2026-07-22

Traefik, a popular cloud-native application proxy, contains a security flaw in how it handles network traffic routing in Kubernetes environments. A user with limited permissions could bypass security restrictions to use unauthorized connection settings, such as high-privilege identity certificates or specialized network protocols. This could allow an attacker to impersonate legitimate services or gain unauthorized access to backend systems. The issue is resolved in versions 3.6.23 and 3.7.7.

Technologies: [github.com/traefik/traefik (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 5.3, published 22 July 2026.

**Which products and versions are affected?** github.com/traefik/traefik (Go) >= 3.6.0, <= 3.6.22.

**Is there a fix for This vulnerability?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run github.com/traefik/traefik (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.

## Technical details

An incorrect authorization vulnerability (CWE-863) exists in Traefik's Kubernetes CRD provider. While the 'crossProviderNamespaces' allowlist is correctly enforced for HTTP references, it is bypassed for IngressRouteTCP 'serversTransport' references. A low-privileged Kubernetes user in a restricted namespace can reference a file-provider 'TCPServersTransport' (e.g., 'foo@file'). This allows the attacker to utilize privileged backend mTLS client certificates, SPIFFE identities, or PROXY-protocol settings defined by the operator. The vulnerability is exploited by creating an IngressRouteTCP resource that points to a transport configuration the namespace is not authorized to use. The fix, implemented in versions 3.6.23 and 3.7.7, applies the allowlist validation to TCP transport references.

## Affected products

- traefik traefik 3.6.0 - 3.6.22, 3.7.0 - 3.7.6

## Timeline

- 2026-07-09: advisory: Original advisory GHSA-42cj-m3vj-89wv published
- 2026-07-22: advisory: Duplicate advisory GHSA-7m3p-wc52-rmc6 published
- 2026-08-05: other: Duplicate advisory GHSA-7m3p-wc52-rmc6 withdrawn

## References

- [https://github.com/traefik/traefik/security/advisories/GHSA-42cj-m3vj-89wv](https://github.com/traefik/traefik/security/advisories/GHSA-42cj-m3vj-89wv)
- [https://github.com/traefik/traefik/commit/26c96a3935cafb473f4a5bae1886560d9aa4e4f0](https://github.com/traefik/traefik/commit/26c96a3935cafb473f4a5bae1886560d9aa4e4f0)
- [https://www.vulncheck.com/advisories/traefik-before-ingressroutetcp-serverstransport-namespace-bypass](https://www.vulncheck.com/advisories/traefik-before-ingressroutetcp-serverstransport-namespace-bypass)

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- [Traefik HTTP request smuggling via unrestricted protocol upgrade](https://junglewise.ai/threats/cve-2026-88008-traefik-http-request-smuggling-via-unrestricted-protocol-upgrade)