UBUNTU-CVE-2026-6104

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UBUNTU-CVE-2026-6104

Summary:

Details: In PHP versions 8.4.* before 8.4.21 and 8.5.* before 8.5.6, when an encoding name containing an embedded NUL byte is passed to mb_convert_encoding() or related mbstring functions, the code incorrectly assumes that when strncasecmp() returns 0 it means the strings have the same length. This can lead to out-of-bounds read of global memory, potentially causing a crash or information disclosure or crash. Affected functions include mb_convert_encoding(), mb_detect_encoding(), mb_convert_variables(), and mb_detect_order(), as well as the mbstring.detect_order and mbstring.http_output INI settings.

References: https://ubuntu.com/security/CVE-2026-6104, https://www.cve.org/CVERecord?id=CVE-2026-6104, https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53, https://ubuntu.com/security/notices/USN-8336-1