Improper Neutralization of Special Elements in Output Used by a Downstream Component in Traefik - CVE-2026-29777
Published: May 5, 2026
Vulnerability identifier: #VU129668
CSH Severity: Low
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-29777
CWE-ID: CWE-74
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Traefik
Traefik
Software vendor:
Containous
Containous
Description
The vulnerability allows a remote user to redirect traffic for victim hostnames to attacker-controlled backends.
The vulnerability exists due to improper neutralization of special elements in output used by a downstream component in the Kubernetes Gateway provider rule builder when processing tenant-controlled HTTPRoute header or query parameter match values. A remote privileged user can inject backtick-delimited rule tokens into generated router rules to redirect traffic for victim hostnames to attacker-controlled backends.
In shared gateway deployments, the issue can bypass listener hostname constraints and enable cross-tenant routing hijack.
Remediation
Install security update from vendor's website.