Description
The default session serializer in PHP 5.2 through 5.2.13 and 5.3 through 5.3.2 does not properly handle the PS_UNDEF_MARKER marker, which allows context-dependent attackers to modify arbitrary session variables via a crafted session variable name.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 5.0 | php5 | 5.2.6.dfsg.1-1+lenny9 | DSA-2089-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | php +18 | 5.1.6-27.el5_5.3 | RHSA-2010:0919 |
| RHEL 4 | php +13 | 4.3.9-3.31 | RHSA-2010:0919 |
Advisories 2
- RHSA-2010:0919 Red Hat Security Advisory: php security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-2089-1 php5 - several vulnerabilities Debian Security (DSA / DLA) · Mar 9, 2026
References
- http://php-security.org/2010/05/31/mops-2010-060-php-session-serializer-session-data-injection-vulnerability/index.html
- DSA-2089 vendor-advisory
- RHSA-2010:0919 vendor-advisory
- 42410 third-party-advisory
- SUSE-SR:2010:017 vendor-advisory
- SUSE-SR:2010:018 vendor-advisory
- ADV-2010-3081 vdb-entry