Secunia

Some vulnerabilities have been reported in PHP, where some have an unknown impact and others can be exploited by malicious people to cause a DoS (Denial of Service) or potentially compromise a vulnerable system, and by malicious, local users to bypass certain security restrictions.

1) An input validation error exists within the "ZipArchive::extractTo()" function when extracting ZIP archives. This can be exploited to extract files to arbitrary locations outside the specified directory via directory traversal sequences in a specially crafted ZIP archive.

2) An error in the included PCRE library can be exploited to cause a buffer overflow.

For more information:
SA30916

3) The "BG(page_uid)" and "BG(page_gid)" variables are not initialized, which can be exploited to bypass "safe_mode" restrictions.

4) An error when "safe_mode" is enabled through "php_admin_flag" can be exploited to bypass security restrictions and write to arbitrary local files via a custom "php_value error_log" .htaccess entry.

5) An error in the GD library can be exploited to cause a crash via a specially crafted font file.

This is related to vulnerability #2 in:
SA31409

6) An error exists in the handling of error conditions when processing unicode data within the "mbfl_filt_conv_html_dec()" function in mbfilter_htmlent.c. This can be exploited to cause a heap-based buffer overflow.

Successful exploitation may be possible from remote, but requires that the "mbstring" extension is configured to automatically filter request data.

NOTE: Additionally, a potential buffer overflow in the "memnstr()" function and crashes in the FastCGI functionality and the IMAP toolkit have been fixed.

The vulnerabilities are reported in version 5.2.6. Other versions may also be affected.

Solution
Update to version 5.2.8.

Provided and/or discovered by
1) Stefan Esser
3, 4) The vendor credits Maksymilian Arciemowicz.
6) Moriyoshi Koizumi, reported in a PHP bug by estacuentanolamiro.

Changelog
Further details available in Customer Area

Original Advisory
PHP:
http://www.php.net/ChangeLog-5.php#5.2.7
http://www.php.net/archive/2008.php#id2008-12-07-1

Stefan Esser:
http://www.sektioneins.de/advisories/SE-2008-06.txt

Maksymilian Arciemowicz:
http://securityreason.com/achievement_securityalert/59
http://securityreason.com/achievement_securityalert/57

Moriyoshi Koizumi:
http://lists.grok.org.uk/pipermail/full-disclosure/2008-December/066556.html

Other references
Further details available in Customer Area

Deep Links
Links available in Customer Area