Bug 1340738 (CVE-2016-5094) - CVE-2016-5094 php: Integer overflow in php_html_entities()
Summary: CVE-2016-5094 php: Integer overflow in php_html_entities()
Alias: CVE-2016-5094
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1340745
Blocks: Embargoed1339953
TreeView+ depends on / blocked
Reported: 2016-05-30 08:33 UTC by Adam Mariš
Modified: 2019-09-29 13:50 UTC (History)
13 users (show)

Fixed In Version: php 5.5.36, php 5.6.22
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2016-06-07 09:49:01 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2016:2750 0 normal SHIPPED_LIVE Moderate: rh-php56 security, bug fix, and enhancement update 2016-11-15 16:40:02 UTC

Description Adam Mariš 2016-05-30 08:33:53 UTC
An integer overflow vulnerability in php_html_entities() was found, allowing to construct string with length outside of integer range.

Upstream bug:


Upstream patch:


CVE assignment:


Comment 1 Adam Mariš 2016-05-30 08:46:59 UTC
Created php tracking bugs for this issue:

Affects: fedora-all [bug 1340745]

Comment 2 Fedora Update System 2016-06-03 15:22:11 UTC
php-5.6.22-1.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.

Comment 3 Tomas Hoger 2016-06-07 09:49:01 UTC
This isn't very practical issue because of the default memory limits set in PHP.  To trigger this, attacker needs to be able to provide sufficiently large input (more than 300MB or 350MB depending on flags used when calling htmlspecialchars() function) that would cause the PHP internal function php_escape_html_entities_ex() to generate output of more than 2GB.  That's not possible in the default configuration of the Red Hat PHP packages, which limits memory a script can use to 128MB.

Additionally, in PHP versions prior to 5.4, length variables (oldlen, newlen) in php_escape_html_entities_ex() are of type int, while they are size_t in 5.4 and newer.  The int variables are casted to size_t when calling emalloc() or erealloc(), leading to attempt to allocate close to SIZE_MAX memory, which fails.  Hence in PHP 5.3 and earlier, php_escape_html_entities_ex() can't return string large enough to trigger this flaw.

In affected versions, this can be mitigated by setting proper memory_limit rather than executing scripts without any limit.

Comment 4 errata-xmlrpc 2016-11-15 11:40:56 UTC
This issue has been addressed in the following products:

  Red Hat Software Collections for Red Hat Enterprise Linux 6
  Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUS
  Red Hat Software Collections for Red Hat Enterprise Linux 7
  Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUS
  Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUS

Via RHSA-2016:2750 https://rhn.redhat.com/errata/RHSA-2016-2750.html

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