SB2026082156 - Inconsistent interpretation of HTTP requests in Traefik

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Main Vulnerability Database SB2026082156

SB2026082156 - Inconsistent interpretation of HTTP requests in Traefik

Published: August 21, 2026

Security Bulletin ID SB2026082156
CSH Severity
High
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

High 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Inconsistent interpretation of HTTP requests (CVE-ID: CVE-2026-71324)

CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

CVSSv4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to poison cross-user HTTP responses and disclose sensitive information.

The vulnerability exists due to inconsistent interpretation of HTTP requests in Traefik\'s default reverse proxy shared backend keep-alive pool when forwarding HTTP/2 or HTTP/3 CONNECT requests with a body to an HTTP/1.1 upstream over a shared net/http.Transport. A remote attacker can send a specially crafted CONNECT request to poison cross-user HTTP responses and disclose sensitive information.

Exploitation requires an HTTP/2 or HTTP/3 frontend and an upstream that returns a keep-alive non-2xx response to the forwarded CONNECT request without draining the body.


Remediation

Install update from vendor's website.

References