What is CVE-2026-111811?

CVE-2026-111811 is a critical-severity vulnerability in Apache Software Foundation Traffic Server, classified under Missing Authentication for Critical Function. CVSS score: 9.0/10. Published 2026-10-21.

How severe is CVE-2026-111811?

Critical severity. CVSS v3 base score is 9.0 out of 10.

Auth bypass in Apache Software Foundation Traffic Server

CVE-2026-111811

Apache Traffic Server's experimental tsmemcache plugin allows unauthenticated network read, write, and deletion of the shared proxy 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: Broken Authentication

Published 2026-10-21 · last modified 2026-10-22.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

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

Apache Software Foundation Traffic Server — versions 10.2.0

Weakness classification (CWE)

CWE-306 — Missing Authentication for Critical Function

References

lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kc (vendor-advisory)

Frequently asked questions

What is CVE-2026-111811?: CVE-2026-111811 is a critical-severity vulnerability in Apache Software Foundation Traffic Server, classified under Missing Authentication for Critical Function. CVSS score: 9.0/10. Published 2026-10-21.
How severe is CVE-2026-111811?: Critical severity. CVSS v3 base score is 9.0 out of 10.