# CVE-2026-88007: Traefik HTTP/3 backend NTLM connection reuse

Source: https://junglewise.ai/threats/cve-2026-88007-traefik-http-3-backend-ntlm-connection-reuse  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-10. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-88007 · Severity: critical · CVSS 9.1 · Published 2026-09-10

Traefik is a reverse proxy and load balancer commonly used in containerized environments. When HTTP/3 is enabled, the proxy fails to properly isolate authentication sessions for backends using NTLM or Kerberos authentication tied to persistent TCP connections. An attacker can reuse a victim's authenticated backend connection without credentials, allowing unauthorized access to sensitive data and the ability to perform actions as the victim.

Technologies: [github.com/traefik/traefik (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik), [github.com/traefik/traefik/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik-v2), [github.com/traefik/traefik/v3 (Go)](https://junglewise.ai/threats/technologies/github-com-traefik-traefik-v3). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-88007 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88007 being exploited in the wild.

**How severe is CVE-2026-88007?** Critical severity, with a CVSS score of 9.1, published 10 September 2026.

**Which products and versions are affected?** github.com/traefik/traefik (Go) SEMVER:introduced=0; github.com/traefik/traefik/v2 (Go) >= 2.11.0, < 2.11.57, SEMVER:introduced=2.11.0,fixed=2.11.57; github.com/traefik/traefik/v3 (Go) >= 3.0.0, < 3.7.13, SEMVER:introduced=3.0.0,fixed=3.7.13.

**Is there a fix for CVE-2026-88007?** Yes. github.com/traefik/traefik/v2 (Go): upgrade to 2.11.57 or later; github.com/traefik/traefik/v3 (Go): upgrade to 3.7.13 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-88007 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-88007?** Check whether you run github.com/traefik/traefik (Go), github.com/traefik/traefik/v2 (Go) or github.com/traefik/traefik/v3 (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/traefik/traefik/v2 (Go): upgrade to 2.11.57 or later

  ```sh
  go get github.com/traefik/traefik/v2@v2.11.57
  ```

- github.com/traefik/traefik/v3 (Go): upgrade to 3.7.13 or later

  ```sh
  go get github.com/traefik/traefik/v3@v3.7.13
  ```


## Technical details

The vulnerability is a protocol-parity bug in HTTP/3 connection context initialization. HTTP/1.1 and HTTP/2 properly call service.AddTransportOnContext() to create a per-connection transport holder for NTLM/Negotiate isolation, but the HTTP/3 handler in server_entrypoint_tcp_http3.go omits this call. When kerberosRoundTripper checks for the transportKey context value and finds it missing, it falls back to the shared OriginalRoundTripper. An attacker can then send an unauthenticated HTTP/3 request that reuses the same backend TCP connection a victim previously authenticated to via NTLM or Negotiate, inheriting the victim's credentials without sending authorization headers. The attack requires HTTP/3 to be enabled on the entrypoint, a routed backend using connection-bound NTLM/Negotiate auth, and backend connection reuse. Patches available in v2.11.57 and v3.7.13.

## Affected products

- Traefik Traefik 2.11.0 to 2.11.56, 3.0.0 to 3.7.12

## Identifiers

- CVE-2026-88007
- GHSA-qqjf-53cj-pwvv
- GO-2026-6466

## Timeline

- 2026-09-07: disclosed: Published on GitHub Advisory Database
- 2026-09-10: advisory: Advisory updated with additional details
- 2026-09-01: patched: Patches released in v2.11.57 and v3.7.13

## References

- [https://api.github.com/users/OneZ3r0](https://api.github.com/users/OneZ3r0)
- [https://github.com/OneZ3r0](https://github.com/OneZ3r0)
- [https://api.github.com/users/OneZ3r0/gists%7B/gist_id%7D](https://api.github.com/users/OneZ3r0/gists%7B/gist_id%7D)
- [https://api.github.com/users/OneZ3r0/repos](https://api.github.com/users/OneZ3r0/repos)
- [https://avatars.githubusercontent.com/u/91706949?v=4](https://avatars.githubusercontent.com/u/91706949?v=4)
- [https://api.github.com/users/OneZ3r0/events%7B/privacy%7D](https://api.github.com/users/OneZ3r0/events%7B/privacy%7D)

## Related threats

- [Traefik BasicAuth singleflight username enumeration via timing oracle](https://junglewise.ai/threats/cve-2026-88010-traefik-basicauth-singleflight-username-enumeration-via-timing)
- [Traefik readTimeout not enforced on HTTP/3 connections](https://junglewise.ai/threats/cve-2026-88012-traefik-readtimeout-not-enforced-on-http-3-connections)
- [Traefik ForwardAuth identity spoofing via header alias](https://junglewise.ai/threats/cve-2026-88011-traefik-forwardauth-identity-spoofing-via-header-alias)
- [Traefik rootless HTTP/1 request-target routing bypass](https://junglewise.ai/threats/cve-2026-88009-traefik-rootless-http-1-request-target-routing-bypass)
- [Traefik HTTP request smuggling via unrestricted protocol upgrade](https://junglewise.ai/threats/cve-2026-88008-traefik-http-request-smuggling-via-unrestricted-protocol-upgrade)