TI-2026-05348 Aliases CVE-2026-6104

Global buffer over-read in mb_convert_encoding() with attacker-supplied encoding

LOW 34CWE-125Published 2026-05-10 · Updated 2026-07-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: Present
Impact type: —
Confidentiality · integrity · availability: Low · None · Low
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00469 40th percentileScored 2026-11-07

Fix Fixed PHP (PHP Group): 8.4.21, 8.5.6Red Hat: 1 advisory

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
PHP Group	PHP	before 8.4.21; before 8.5.6	8.4.21, 8.5.6	Patch available	CNA

PHP VendorPHP Group Affected before 8.4.21; before 8.5.6 Fixed in 8.4.21, 8.5.6 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:php:php::::::::	8.4.0 to before 8.4.21; 8.5.0 to before 8.5.6	Vulnerable	PHP

cpe:2.3:a:php:php:*:*:*:*:*:*:*:* Versions 8.4.0 to before 8.4.21; 8.5.0 to before 8.5.6 Vulnerable ·PHP

Remediation

Fix · CNA PHP (PHP Group) Fixed in 8.4.21, 8.5.6

Red Hat 1 advisory

RHSA-2026:22649 Released 2026-06-02 · Red Hat rating Important
php8.4 security update
- Red Hat Enterprise Linux AppStream (v. 10) php8.4-8.4.21-1.el10_2, php8.4-bcmath-8.4.21-1.el10_2, php8.4-cli-8.4.21-1.el10_2 +22

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-05-10
PHP 8.4.21, 8.5.6
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2026-06377 DoS attack via DOMNode::C14N()Priority LOW 34
Show all 2 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux AppStream (v. 10)	Fixed	RHSA-2026:22649

Not affected: 6 products

Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Hardened Images

Timeline

2026-10-02 Threatist record created from CVE-2026-6104

References

Advisory 1

https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53

TI-2024-04260 Argument Injection in PHP-CGI KEVCVSS 3.1CRITICAL 9.8
TI-2026-78794 PHP remote code execution via stale global state KEVCVSS 4.0CRITICAL 9.2
TI-2026-78793 Out-of-memory handling flaw in PHP allows remote code execution KEVCVSS 4.0CRITICAL 9.2
TI-2024-01743 Command injection via array-ish $command parameter of proc_open() CVSS 3.1CRITICAL 9.4
TI-2022-13555 PDO::quote() may return unquoted string CVSS 3.1CRITICAL 9.1
TI-2024-10408 Reference counting in php_request_shutdown causes Use-After-Free CVSS 4.0CRITICAL 9.2

See all 107 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences