CVE-2026-111809 Apache Software Foundation CVE debrief

Who should care

Defenders and administrators of Apache Traffic Server should assess exposure and upgrade to patched versions to prevent request smuggling attacks. They should review and update affected versions, monitor for potential request smuggling attacks, and verify their systems. Security teams and vulnerability management teams should also be aware of this vulnerability and take necessary actions to protect their systems.

Why it matters

Apache Traffic Server is vulnerable to request smuggling via HEAD requests with Content-Length or Transfer-Encoding headers. Defenders and administrators should assess exposure and upgrade to patched versions to prevent potential request smuggling attacks.

• Potential for request smuggling attacks
• Need to upgrade to patched versions
• Review and update affected versions
• Monitor for potential request smuggling attacks

Technical summary

Apache Traffic Server allows request smuggling via HEAD requests that carry Content-Length or Transfer-Encoding headers. This issue affects Apache Traffic Server versions 8.0.0 through 8.1.11, 9.0.0 through 9.2.15, 10.0.0 through 10.1.4, and 10.2.0. The vulnerability can be exploited by attackers to smuggle requests, potentially leading to security breaches. Defenders and administrators should assess their exposure and upgrade to patched versions to prevent request smuggling attacks. The vulnerability has been publicly disclosed, and users are advised to take necessary precautions.

Defensive priority

Upgrade to patched versions to prevent request smuggling attacks

Recommended defensive actions

• Upgrade to version 9.2.16, 10.1.5, or 10.2.1
• Review and update affected versions
• Monitor for potential request smuggling attacks
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability and affected versions. The vulnerability has been publicly disclosed, and users are advised to take necessary precautions. There is no evidence of exploitation in the wild, but defenders should verify their systems and plan for updates. The CVE Program and NVD provide official guidance on this vulnerability.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.