Input validation error in PHP - CVE-2016-4538
Published: October 30, 2018 / Updated: June 8, 2025
Vulnerability identifier: #VU110264
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2016-4538
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.
The bcpowmod function in ext/bcmath/bcmath.c in PHP before 5.5.35, 5.6.x before 5.6.21, and 7.x before 7.0.6 modifies certain data structures without considering whether they are copies of the _zero_, _one_, or _two_ global variable, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted call.
Affected software
PHP
Fedora
php
Fedora
php
How to mitigate CVE-2016-4538
Install update from vendor's website.
PHP - addressed in versions 5.6.21, 7.0.6
php - addressed in versions 5.6.21-1.fc22, 5.6.21-1.fc24
php - addressed in versions 5.6.21-1.fc22, 5.6.21-1.fc24
External References
- http://lists.fedoraproject.org/pipermail/package-announce/2016-May/183736.html
- http://lists.opensuse.org/opensuse-updates/2016-05/msg00086.html
- http://lists.opensuse.org/opensuse-updates/2016-06/msg00027.html
- http://php.net/ChangeLog-5.php
- http://php.net/ChangeLog-7.php
- http://rhn.redhat.com/errata/RHSA-2016-2750.html
- http://www.debian.org/security/2016/dsa-3602
- http://www.openwall.com/lists/oss-security/2016/05/05/21
- http://www.securityfocus.com/bid/90173
- https://bugs.php.net/bug.php?id=72093
- https://git.php.net/?p=php-src.git;a=commit;h=d650063a0457aec56364e4005a636dc6c401f9cd
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05240731
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05320149
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05390722
- https://security.gentoo.org/glsa/201611-22