---
title: "CVE-2026-88007: Traefik HTTP/3 Backend NTLM Connection Reuse"
url: https://erroneo.us/security/cve/CVE-2026-88007/
description: "CVE-2026-88007 (github.com/traefik/traefik/v3 (Go)): Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-10
date_modified: 2026-09-10
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-88007"
kev: false
cvss: 9.1
epss: 0.006
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-88007: Traefik HTTP/3 Backend NTLM Connection Reuse

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.6% , percentile 48: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 48% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/traefik/traefik/v3 (Go) >= 3.0.0, < 3.7.13, fixed in 3.7.13 ; github.com/traefik/traefik/v2 (Go) >= 2.11.0, < 2.11.57, fixed in 2.11.57 . Check your lockfile, including transitive dependencies.

## What it is

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

## Affected packages

- Go `github.com/traefik/traefik/v3` >= 3.0.0, < 3.7.13 → fixed: 3.7.13
- Go `github.com/traefik/traefik/v2` >= 2.11.0, < 2.11.57 → fixed: 2.11.57

## Affected products (CVE record)

- traefik traefik: >= 2.11.0, < 2.11.57, >= 3.0.0, < 3.7.13

## Severity

- GitHub_M CVSS 4.0: 9.1 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`
- GitHub CVSS 4.0: 9.1 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.60% probability of exploitation activity in the next 30 days; percentile 48.

## Sources

- [GitHub Advisory GHSA-qqjf-53cj-pwvv](https://github.com/advisories/GHSA-qqjf-53cj-pwvv)
- [CVE.org record CVE-2026-88007](https://www.cve.org/CVERecord?id=CVE-2026-88007)
- [NVD entry CVE-2026-88007](https://nvd.nist.gov/vuln/detail/CVE-2026-88007)
- [github.com](https://github.com/traefik/traefik/security/advisories/GHSA-qqjf-53cj-pwvv)
- [github.com](https://github.com/traefik/traefik/pull/13812)
- [github.com](https://github.com/traefik/traefik/commit/ff39c47d7459dec9cd8de63c1a4e7aa7315bdc1c)
- [github.com](https://github.com/traefik/traefik/releases/tag/v2.11.57)
- [github.com](https://github.com/traefik/traefik/releases/tag/v3.7.13)

---
Source page: https://erroneo.us/security/cve/CVE-2026-88007/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt