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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
None
No data modification
Availability
Low
Partial disruption
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products 2
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Php Php
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
|
8.4.0
|
8.4.21
|
|
Php Php
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
|
8.5.0
|
8.5.6
|
References 5
https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53
security@php.net
https://access.redhat.com/errata/RHSA-2026:22649
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/security/cve/CVE-2026-6104
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://bugzilla.redhat.com/show_bug.cgi?id=2468573
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6104.json
0b0ca135-0b70-47e7-9f44-1890c2a1c46c