CVE-2025-55702 Apache Software Foundation CVE debrief

Who should care

Defenders 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 exposure and upgrade to fixed versions 9.2.16, 10.1.5, or 10.2.1. Security teams and vulnerability management teams should review the official advisory and CVE record to validate affected scope, severity, and vendor guidance. Operators and administrators of affected systems should plan

Why it matters

Apache Traffic Server vulnerability allows request smuggling, potentially impacting response desynchronization; defenders should assess exposure and upgrade to fixed versions.

• Potential desynchronization of responses for other users
• Request smuggling attacks via unread Expect: 100-continue request bodies
• Need to verify inventory and upgrade to fixed versions

Technical summary

Apache Traffic Server vulnerability allows an attacker to smuggle requests past a front-end proxy and desynchronize responses for other users when a client sends a POST with Expect: 100-continue and the origin answers before reading the body. 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. Defenders should assess exposure and upgrade to fixed versions 9.2.16, 10.1.5, or 10.2.1 to prevent potential request smuggling attacks. The vulnerability can be exploited by an attacker behind a front-end proxy that shares connections to Traffic Server.

Defensive priority

Upgrade to fixed versions 9.2.16, 10.1.5, or 10.2.1; assess exposure and verify inventory.

Recommended defensive actions

• Upgrade Apache Traffic Server to version 9.2.16, 10.1.5, or 10.2.1
• Assess exposure and verify inventory of Apache Traffic Server instances
• Monitor for potential request smuggling attacks
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

Official CVE Program record and NVD vulnerability detail provide information on the vulnerability and affected versions. The CVE record was published on 2026-10-21T18:24:21.377Z and has not been modified since then. Defenders should verify inventory and assess exposure to ensure that affected versions are upgraded to fixed versions. The official advisory and CVE record should be reviewed to validate affected scope, severity, and vendor guidance.

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.