Bug 2468573 (CVE-2026-6104)

Summary:	CVE-2026-6104 php: global buffer over-read in mb_convert_encoding() with attacker-supplied encoding
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	jkoehler, lphiri, rhel-process-autobot, sdawley, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in PHP. When an encoding name containing an embedded NUL byte is passed to `mb_convert_encoding()` or related mbstring functions, an out-of-bounds read of only 1 byte can occur due to the incorrect processing of string lengths. This issue can cause a denial of service or limited information disclosure.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-05-10 06:01:25 UTC

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.

Comment 3 errata-xmlrpc 2026-06-02 22:08:00 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:22649 https://access.redhat.com/errata/RHSA-2026:22649