CVE-2026-6104
Global buffer over-read in mb_convert_encoding() with attacker-supplied encoding
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.
INFO
Published Date :
May 10, 2026, 6:16 a.m.
Last Modified :
July 24, 2026, 8:10 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 3.1 | HIGH | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | ||||
| CVSS 4.0 | MEDIUM | dd77f84a-d19a-4638-8c3d-a322d820ed2b | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update PHP to version 8.4.21 or later.
- Update PHP to version 8.5.6 or later.
- Verify mbstring function behavior.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6104.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6104 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6104
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6104 vulnerability anywhere in the article.
-
CybersecurityNews
Critical PHP SOAP Extension Vulnerabilities Enables Remote Code Execution Attacks
A serious cluster of vulnerabilities has been uncovered in PHP’s core string processing and ext-soap components, putting numerous web servers at immediate risk of total takeover. While the SOAP extens ... Read more
The following table lists the changes that have been made to the
CVE-2026-6104 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Translation Title: PHP de PHP Group, Description: En versiones de PHP 8.4.* anteriores a 8.4.21 y 8.5.* anteriores a 8.5.6, cuando un nombre de codificación que contiene un byte NUL incrustado se pasa a mb_convert_encoding() o funciones mbstring relacionadas, el código asume incorrectamente que cuando strncasecmp() devuelve 0 significa que las cadenas tienen la misma longitud. Esto puede llevar a una lectura fuera de límites de la memoria global, lo que podría causar un fallo o revelación de información o un fallo. Las funciones afectadas incluyen mb_convert_encoding(), mb_detect_encoding(), mb_convert_variables() y mb_detect_order(), así como las configuraciones INI mbstring.detect_order y mbstring.http_output. -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 15, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 10', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:6'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 6', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 7', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 8', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:hummingbird:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Hardened Images', 'defaultStatus': 'unaffected'}] [{'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 10', 'versions': [{'status': 'unaffected', 'version': '0:8.4.21-1.el10_2', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'php8.4', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 10', 'packageName': 'php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:6'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 6', 'packageName': 'php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 7', 'packageName': 'php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 8', 'packageName': 'php:7.4/php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 8', 'packageName': 'php:8.2/php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'packageName': 'php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'packageName': 'php:8.2/php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'packageName': 'php:8.3/php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:hummingbird:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Hardened Images', 'packageName': 'php', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}] -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 10', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:6'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 6', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 7', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 8', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:hummingbird:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Hardened Images', 'defaultStatus': 'unaffected'}] Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H Added CWE CWE-125 Added Reference https://access.redhat.com/errata/RHSA-2026:22649 Added Reference https://access.redhat.com/security/cve/CVE-2026-6104 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2468573 Added Reference https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6104.json -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-6104', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-11T13:04:44.572023Z'} -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'PHP Group', 'product': 'PHP', 'versions': [{'status': 'affected', 'version': '8.4.*', 'lessThan': '8.4.21', 'versionType': 'semver'}, {'status': 'affected', 'version': '8.5.*', 'lessThan': '8.5.6', 'versionType': 'semver'}], 'packageName': 'mbstring', 'defaultStatus': 'unaffected'}] -
Initial Analysis by [email protected]
May. 12, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.4.0 up to (excluding) 8.4.21 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.5.0 up to (excluding) 8.5.6 Added Reference Type PHP Group: https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53 Types: Vendor Advisory -
New CVE Received by [email protected]
May. 10, 2026
Action Type Old Value New Value 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. Added CVSS V4.0 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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:M/U:Amber Added CWE CWE-125 Added Reference https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53