Critical severity · published Oct 21, 2026
CVE-2026-111809
Apache Traffic Server: HEAD requests carrying Content-Length or Transfer-Encoding enable request smuggling
New
9.3
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
High
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 12% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AT
Apache Traffic Server · Apache Software Foundation
8.0.0 through 8.1.11; 9.0.0 through 9.2.15; 10.0.0 through 10.1.4; 10.2.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-111809
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-111809
lists.apache.org
https://lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kc
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