Vulnerability · Published Oct 21, 2026 · Assigned by apache

CVE-2026-111809Apache Traffic Server: HEAD requests carrying Content-Length or Transfer-Encoding enable request smuggling

Critical 9.3

In plain English

A critical-severity security flaw in Apache Traffic Server from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities).

Severity (CVSS 3.1)9.3Critical

Exploit odds (30 days)0.2%top 87.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Apache Traffic Server allows request smuggling via HEAD requests that carry Content-Length or Transfer-Encoding. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0. Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	trafficserver	no fix listed	DEBIAN-CVE-2026-111809
Ubuntu:24.04:LTS	trafficserver	no fix listed	UBUNTU-CVE-2026-111809

Affected products (as reported)

Vendor	Product	Versions
Apache Software Foundation	Apache Traffic Server	8.0.0 – through 8.1.119.0.0 – through 9.2.1510.0.0 – through 10.1.410.2.0

Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N

References

https://lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kc vendor-advisory