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.
Published: 2026-05-10
Score: 6.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DSA Debian DSA DSA-6256-1 php8.4 security update
History

Tue, 12 May 2026 17:45:00 +0000

Type Values Removed Values Added
First Time appeared Php
Php php
CPEs cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
Vendors & Products Php
Php php
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'}


Mon, 11 May 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Sun, 10 May 2026 07:45:00 +0000

Type Values Removed Values Added
First Time appeared Php Group
Php Group php
Vendors & Products Php Group
Php Group php

Sun, 10 May 2026 06:00:00 +0000

Type Values Removed Values Added
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.
Title Global buffer over-read in mb_convert_encoding() with attacker-supplied encoding
Weaknesses CWE-125
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:L/SI:N/SA:L/RE:M/U:Amber'}


cve-icon MITRE

Status: PUBLISHED

Assigner: php

Published:

Updated: 2026-05-11T13:04:58.462Z

Reserved: 2026-04-11T04:15:03.938Z

Link: CVE-2026-6104

cve-icon Vulnrichment

Updated: 2026-05-11T13:04:53.269Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-10T06:16:07.397

Modified: 2026-05-12T17:35:59.777

Link: CVE-2026-6104

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-10T07:30:05Z

Weaknesses