Vulnerability in Apache Software Foundation Traffic Server

CVE-2025-31699

Apache Traffic Server can return an origin connection to the shared pool while the origin is still waiting on a request body the client declared but never fully sent, including when the client used Expect: 100-continue. The origin then reads a later request on that connection as leftover body data, which lets an attacker smuggle requests past ATS access controls, disrupt other users' requests, or poison the cache. 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.

Vulnerability class: HTTP Request Smuggling

Published .

CVSS v3 metric

CVSS v3 base score 8.9 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-31699?
CVE-2025-31699 is a high-severity vulnerability in Apache Software Foundation Traffic Server, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 8.9/10. Published 2026-10-21.
How severe is CVE-2025-31699?
High severity. CVSS v3 base score is 8.9 out of 10.