The imagetruecolortopalette function in ext/gd/gd.c in PHP before 5.6.25 and 7.x before 7.0.10 does not properly validate the number of colors, which allows remote attackers to cause a denial of service (select_colors allocation error and out-of-bounds write) or possibly have unspecified other impact via a large value in the third argument.
http://openwall.com/lists/oss-security/2016/09/02/9
http://rhn.redhat.com/errata/RHSA-2016-2750.html
http://www.php.net/ChangeLog-5.php
http://www.php.net/ChangeLog-7.php
http://www.securityfocus.com/bid/92755
http://www.securitytracker.com/id/1036680
https://bugs.php.net/bug.php?id=72697
https://github.com/php/php-src/commit/28022c9b1fd937436ab67bb3d61f652c108baf96
https://github.com/php/php-src/commit/b6f13a5ef9d6280cf984826a5de012a32c396cd4?w=1
Source: MITRE
Published: 2016-09-12
Updated: 2020-11-16
Type: CWE-787
Base Score: 7.5
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 10
Severity: HIGH
Base Score: 9.8
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 3.9
Severity: CRITICAL