Description
Integer overflow in the ap_pregsub function in server/util.c in the Apache HTTP Server 2.0.x through 2.0.64 and 2.2.x through 2.2.21, when the mod_setenvif module is enabled, allows local users to gain privileges via a .htaccess file with a crafted SetEnvIf directive, in conjunction with a crafted HTTP request header, leading to a heap-based buffer overflow.
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 14 | apache2 | 2.2.21-4 | — |
| Debian 13 | apache2 | 2.2.21-4 | — |
| Debian 12 | apache2 | 2.2.21-4 | — |
| Debian 6.0 | apache2 | 2.2.16-6+squeeze6 | DSA-2405-1 |
| Debian 5.0 | apache2 | 2.2.9-10+lenny12 | DSA-2405-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | httpd +3 | 2.2.15-15.el6_2.1 | RHSA-2012:0128 |
| RHEL 6 | mod_ssl | 1:2.2.15-15.el6_2.1 | RHSA-2012:0128 |
| RHEL 5 | httpd +2 | 2.2.3-63.el5_8.1 | RHSA-2012:0323 |
| RHEL 5 | mod_ssl | 1:2.2.3-63.el5_8.1 | RHSA-2012:0323 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat JBoss Web Server 1 | httpd +2 | 2.2.17-15.4.ep5.el5 | RHSA-2012:0542 |
| Red Hat JBoss Web Server 1 | httpd-tools | 2.2.17-15.4.ep5.el6 | RHSA-2012:0542 |
| Red Hat JBoss Web Server 1 | mod_ssl | 1:2.2.17-15.4.ep5.el5 | RHSA-2012:0542 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | apache2 | 2.4.23-4.1 | openSUSE-SU-2024:10268-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- Apache < 2.0.64 / < 2.2.21 mod_setenvif - Integer Overflow EDB-41769 · dos · Nov 2, 2011
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 5
- RHSA-2012:0323 Red Hat Security Advisory: httpd security update Red Hat Security Advisories (RHSA) · Aug 5, 2026
- RHSA-2012:0128 Red Hat Security Advisory: httpd security update Red Hat Security Advisories (RHSA) · Aug 5, 2026
- RHSA-2012:0542 Red Hat Security Advisory: httpd security and bug fix update Red Hat Security Advisories (RHSA) · May 15, 2026
- DSA-2405-1 apache2 - multiple issues Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10268-1 apache2-2.4.23-4.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- HPSBMU02786 vendor-advisory
- SSRT100966 vendor-advisory
- https://bugs.launchpad.net/ubuntu/+source/apache2/+bug/811422
- http://www.halfdog.net/Security/2011/ApacheModSetEnvIfIntegerOverflow/DemoExploit.html
- RHSA-2012:0543 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=750935
- SSRT100772 vendor-advisory
- RHSA-2012:0128 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/cpujan2015-1972971.html
- 45793 third-party-advisory
- 50494 vdb-entry
- RHSA-2012:0542 vendor-advisory
- 1026267 vdb-entry
- APPLE-SA-2012-09-19-2 vendor-advisory
- http://support.apple.com/kb/HT5501
- http://www.oracle.com/technetwork/topics/security/cpujul2012-392727.html
- http://www.fujitsu.com/global/support/software/security/products-f/interstage-201303e.html
- 20111102 Integer Overflow in Apache ap_pregsub via mod-setenvif mailing-list
- http://www.halfdog.net/Security/2011/ApacheModSetEnvIfIntegerOverflow/
- 76744 vdb-entry
- HPSBUX02761 vendor-advisory
- MDVSA-2013:150 vendor-advisory
- 48551 third-party-advisory
- DSA-2405 vendor-advisory
- apache-http-appregsub-bo(71093) vdb-entry
- MDVSA-2012:003 vendor-advisory
- [httpd-cvs] 20190815 svn commit: r1048742 [2/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20190815 svn commit: r1048743 [2/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20190815 svn commit: r1048743 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20190815 svn commit: r1048742 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20200401 svn commit: r1058586 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20200401 svn commit: r1058586 [2/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20200401 svn commit: r1058587 [2/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20200401 svn commit: r1058587 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilit mailing-list
- [httpd-cvs] 20210330 svn commit: r1073139 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073140 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.ht mailing-list
- [httpd-cvs] 20210330 svn commit: r1888194 [7/13] - /httpd/site/trunk/content/security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073140 [2/4] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.ht mailing-list
- [httpd-cvs] 20210330 svn commit: r1073143 [2/3] - in /websites/staging/httpd/trunk/content: ./ security/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073139 [7/13] - in /websites/staging/httpd/trunk/content: ./ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073149 [8/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/ mailing-list
- [httpd-cvs] 20210330 svn commit: r1073146 [2/3] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities-httpd.xml security/vulnerabilities_22.html security/vulnerabilities_24.html mailing-list
- [httpd-cvs] 20210330 svn commit: r1073149 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/ mailing-list
- [httpd-cvs] 20210603 svn commit: r1075360 [2/3] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabiliti mailing-list
- [httpd-cvs] 20210603 svn commit: r1075360 [1/3] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabiliti mailing-list
- [httpd-cvs] 20210606 svn commit: r1075467 [2/2] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabiliti mailing-list
- [httpd-cvs] 20210606 svn commit: r1075467 [1/2] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabiliti mailing-list
- [httpd-cvs] 20210606 svn commit: r1075470 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-13938.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabiliti mailing-list