CVE-2026-111816 Apache Software Foundation CVE debrief

Who should care

Defenders and administrators of Apache Traffic Server instances, particularly those using 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, should assess their exposure, prioritize remediation, and monitor for suspicious activity. This includes reviewing and updating affected versions, verifying deployments, and implementing compensating controls where necessary.

Why it matters

CVE-2026-111816 allows cache poisoning and response-framing desync in Apache Traffic Server, requiring defenders to assess exposure, prioritize remediation, and monitor for suspicious activity.

• Cache poisoning and response-framing desync can lead to incorrect content being served
• Potential for security bypass and further exploitation
• Requires verification of affected versions and remediation steps
• Upgrade priority to fixed versions to prevent exploitation

Technical summary

Apache Traffic Server incorrectly handles malformed 302 responses with Transfer-Encoding: chunked, allowing cache poisoning and response-framing desync. This occurs because the carve-out for chunked encoding bypasses the parse-error rejection path, leading to potential security issues. The vulnerability affects multiple versions of Apache Traffic Server, requiring defenders to assess exposure and prioritize remediation to prevent exploitation and data integrity issues. Users should upgrade to fixed versions to mitigate the risk.

Defensive priority

Upgrade to fixed versions 9.2.16, 10.1.5, or 10.2.1 to prevent cache poisoning and response desync.

Recommended defensive actions

• Upgrade Apache Traffic Server to version 9.2.16, 10.1.5, or 10.2.1
• Review and update affected 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
• Monitor for and block suspicious 302 responses
• 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, but affected versions and remediation are limited to vendor-provided information. The issue is confirmed in 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. Defenders should verify affected deployments and review vendor guidance for remediation steps.

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.