All vulnerabilities
CVE-2025-55702

Apache Traffic Server: An unread Expect: 100-continue request body is framed as a new request

Apache Software Foundation Apache Traffic Server
Open in ThreatlineRecord JSON
CVSS
8.7High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.25%Chance of exploitation activity in the next 30 days, higher than 15% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published21 Oct 2026Updated 23 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Description

When a client sends a POST with Expect: 100-continue and the origin answers before reading the body, Apache Traffic Server parses the unread body left on the client connection as the next request. An attacker behind a front-end proxy that shares connections to Traffic Server can use this to smuggle requests past the front end and desynchronize responses for other users.

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.

Text from CVE List

Affected versions 4

  • Apache Traffic Serveraffected: 8.0.0 through 8.1.11CVE List
  • Apache Traffic Serveraffected: 9.0.0 through 9.2.15CVE List
  • Apache Traffic Serveraffected: 10.0.0 through 10.1.4CVE List
  • Apache Traffic Serveraffected: 10.2.0CVE List

References 1