Off-by-one in Apache Tomcat - CVE-2026-65927
Published: August 26, 2026
Vulnerability identifier: #VU145383
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-65927
CWE-ID: CWE-193
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass access control.
The vulnerability exists due to an off-by-one error in RewriteValve when processing rewrite rules that use the [N] flag. A remote attacker can trigger rewrite processing to restart at the second rule instead of the first rule to bypass access control.
Affected software
Apache Tomcat
How to mitigate CVE-2026-65927
Install security update from vendor's website.
Apache Tomcat - addressed in versions 9.0.121, 10.1.59, 11.0.25