CVE-2026-59083: Apache Tomcat: Incorrect URL decoding in RewriteValve may allow security control bypass

Analysis on rafaelpfister.ch

Article · October 31, 2026 totemomail 9.5.1: Account takeover in the Web Portal and SSRF via incoming email fixed totemomail 9.5.1 fixes eight security vulnerabilities and brings totemomail in line with the Kiteworks advisories for Email Protection Gateway published at the end of September. Two vulnerabilities can be exploited without authentication: a flaw in the Web Portal password reset process that allows administrator accounts to be taken over, and server-side retrieval of URLs from incoming messages. The release also includes path traversal fixes in the Admin API and Mail API, as well as updated Tomcat and Batik libraries.

Vendor description

Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.24, 10.1.57 or 9.0.120, which fix the issue.

Reference data

Vendor

Apache Software Foundation

Affected products

Apache Tomcat

CVSS 3.1

9.1 (CRITICAL)

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weakness type

CWE-177: Improper Handling of URL Encoding (Hex Encoding)

Published

July 14, 2026

Official sources

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CVE-2026-59083 Apache Tomcat: Incorrect URL decoding in RewriteValve may allow security control bypass

Analysis on rafaelpfister.ch

Vendor description

Reference data

Official sources

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