CVE-2026-6104
This can lead to out-of-bounds read of global memory, potentially causing a crash or information disclosure or crash.
Does this matter?
Lower severity and a low EPSS score (0.47%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 4.0
- 6.3 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:L/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.47% probability · 39th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- php/php
- Source
- security@php.net
References
- https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:22649
- https://access.redhat.com/security/cve/CVE-2026-6104
- https://bugzilla.redhat.com/show_bug.cgi?id=2468573
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6104.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.