Description
Apache httpd 1.3.37, 2.0.59, and 2.2.4 with the Prefork MPM module, allows local users to cause a denial of service by modifying the worker_score and process_score arrays to reference an arbitrary process ID, which is sent a SIGUSR1 signal from the master process, aka "SIGUSR1 killer."
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 | 2.2.4-2 | — |
| Debian 13 | apache2 | 2.2.4-2 | — |
| Debian 12 | apache2 | 2.2.4-2 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | httpd +2 | 2.2.3-7.el5 | RHSA-2007:0556 |
| RHEL 5 | mod_ssl | 1:2.2.3-7.el5 | RHSA-2007:0556 |
| RHEL 4 | httpd +3 | 2.0.52-32.3.ent | RHSA-2007:0662 |
| RHEL 4 | mod_ssl | 1:2.0.52-32.3.ent | RHSA-2007:0662 |
| RHEL 3 | httpd +1 | 2.0.46-68.ent | RHSA-2007:0662 |
| RHEL 3 | mod_ssl | 1:2.0.46-68.ent | RHSA-2007:0662 |
| RHEL 2 | apache +2 | 1.3.27-12.ent | RHSA-2007:0532 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Rhel Application Stack 1 | httpd +2 | 2.0.59-1.el4s1.7 | RHSA-2007:0557 |
| Red Hat Rhel Application Stack 1 | mod_ssl | 1:2.0.59-1.el4s1.7 | RHSA-2007:0557 |
| Red Hat Network Satellite 5 | jabberd | 2.0s10-3.38.rhn | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | java-1.4.2-ibm +1 | 1.4.2.10-1jpp.2.el4 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | jfreechart | 0.9.20-3.rhn | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | openmotif21 | 2.1.30-11.RHEL4.6 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | perl-Crypt-CBC | 2.24-1.el4 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | rhn-apache | 1.3.27-36.rhn.rhel4 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | rhn-modjk-ap13 | 1.2.23-2rhn.rhel4 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | rhn-modperl | 1.29-16.rhel4 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | rhn-modssl | 2.8.12-8.rhn.10.rhel4 | RHSA-2008:0261 |
| Red Hat Network Satellite 5 | tomcat5 | 5.0.30-0jpp_10rh | RHSA-2008:0261 |
| Red Hat Network Satellite 4 | jabberd | 2.0s10-3.37.rhn | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | java-1.4.2-ibm +1 | 1.4.2.10-1jpp.2.el3 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | jfreechart | 0.9.20-3.rhn | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | openmotif21 | 2.1.30-9.RHEL3.8 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | perl-Crypt-CBC | 2.24-1.el3 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | rhn-apache | 1.3.27-36.rhn.rhel3 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | rhn-modjk-ap13 | 1.2.23-2rhn.rhel3 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | rhn-modperl | 1.29-16.rhel3 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | rhn-modssl | 2.8.12-8.rhn.10.rhel3 | RHSA-2008:0524 |
| Red Hat Network Satellite 4 | tomcat5 | 5.0.30-0jpp_10rh | RHSA-2008:0524 |
| Red Hat Network Proxy 5 | jabberd | 2.0s10-3.38.rhn | RHSA-2008:0263 |
| Red Hat Network Proxy 5 | rhn-apache | 1.3.27-36.rhn.rhel4 | RHSA-2008:0263 |
| Red Hat Network Proxy 5 | rhn-modperl | 1.29-16.rhel4 | RHSA-2008:0263 |
| Red Hat Network Proxy 4 | jabberd | 2.0s10-3.37.rhn | RHSA-2008:0523 |
| Red Hat Network Proxy 4 | rhn-apache | 1.3.27-36.rhn.rhel3 | RHSA-2008:0523 |
| Red Hat Network Proxy 4 | rhn-modperl | 1.29-16.rhel3 | RHSA-2008:0523 |
| Red Hat Certificate System 7 | ant | 1.6.5-1jpp_1rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | avalon-logkit | 1.2-2jpp_4rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | axis | 1.2.1-1jpp_3rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | classpathx-jaf | 1.0-2jpp_6rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | classpathx-mail | 1.1.1-2jpp_8rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | geronimo-specs +10 | 1.0-0.M4.1jpp_10rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | jakarta-commons-modeler | 2.0-3jpp_2rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | log4j | 1.2.12-1jpp_1rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | mx4j | 1:3.0.1-1jpp_4rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | pcsc-lite +2 | 1.3.3-3.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | rhpki-ca | 7.3.0-20.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | rhpki-java-tools | 7.3.0-10.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | rhpki-kra | 7.3.0-14.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | rhpki-manage | 7.3.0-19.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | rhpki-native-tools | 7.3.0-6.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | rhpki-tks +1 | 7.3.0-13.el4 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | tomcat5 +5 | 5.5.23-0jpp_4rh.16 | RHSA-2010:0602 |
| Red Hat Certificate System 7 | xerces-j2 | 2.7.1-1jpp_1rh | RHSA-2010:0602 |
| Red Hat Certificate System 7 | xml-commons +1 | 1.3.02-2jpp_1rh | RHSA-2010:0602 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | apache2 | 2.4.49-1.1 | openSUSE-SU-2024:10623-1 |
Advisories 10
- RHSA-2010:0602 Red Hat Security Advisory: Red Hat Certificate System 7.3 security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2008:0524 Red Hat Security Advisory: Red Hat Network Satellite Server security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2008:0523 Red Hat Security Advisory: Red Hat Network Proxy Server security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2008:0261 Red Hat Security Advisory: Red Hat Network Satellite Server security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2007:0556 Red Hat Security Advisory: httpd security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2007:0662 Red Hat Security Advisory: httpd security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2007:0532 Red Hat Security Advisory: apache security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- openSUSE-SU-2024:10623-1 apache2-2.4.49-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- RHSA-2008:0263 Red Hat Security Advisory: Red Hat Network Proxy Server security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2007:0557 Red Hat Security Advisory: httpd security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
References
- 28606 third-party-advisory
- http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=245111
- MDKSA-2007:142 vendor-advisory
- 26822 third-party-advisory
- ADV-2007-4305 vdb-entry
- ADV-2007-3420 vdb-entry
- RHSA-2007:0557 vendor-advisory
- 38939 vdb-entry
- PK52702 vendor-advisory
- MDKSA-2007:140 vendor-advisory
- HPSBUX02273 vendor-advisory
- 25827 third-party-advisory
- 25920 third-party-advisory
- 26993 third-party-advisory
- 28212 third-party-advisory
- http://security.psnc.pl/files/apache_report.pdf
- 1018304 vdb-entry
- 27563 third-party-advisory
- 27732 third-party-advisory
- http://svn.apache.org/viewvc?view=rev&revision=547987
- 103179 vendor-advisory
- 27209 third-party-advisory
- RHSA-2007:0662 vendor-advisory
- 26790 third-party-advisory
- RHSA-2007:0556 vendor-advisory
- http://httpd.apache.org/security/vulnerabilities_20.html
- SUSE-SA:2007:061 vendor-advisory
- 20070529 Apache httpd vulenrabilities mailing-list
- FEDORA-2007-2214 vendor-advisory
- [apache-httpd-dev] 20070622 Re: PID table changes (was Re: svn commit: r547987 - in /httpd/httpd/trunk) mailing-list
- 26759 third-party-advisory
- ADV-2007-3494 vdb-entry
- PK50467 vendor-advisory
- 2007-0026 vendor-advisory
- RHSA-2007:0532 vendor-advisory
- http://httpd.apache.org/security/vulnerabilities_22.html
- https://issues.rpath.com/browse/RPL-1710
- [apache-httpd-dev] 20070629 Re: [PATCH] pid safety checks for 2.2.x mailing-list
- 20090821 VMSA-2009-0010 VMware Hosted products update libpng and Apache HTTP Server mailing-list
- 2814 third-party-advisory
- oval:org.mitre.oval:def:11589 vdb-entry signature
- 27121 third-party-advisory
- 20070619 Apache Prefork MPM vulnerabilities - Report mailing-list
- ADV-2008-0233 vdb-entry
- http://www.fujitsu.com/global/support/software/security/products-f/interstage-200802e.html
- 26211 third-party-advisory
- apache-child-process-dos(35095) vdb-entry
- 26443 third-party-advisory
- [security-announce] 20090820 VMSA-2009-0010 VMware Hosted products update libpng and Apache HTTP Server mailing-list
- http://httpd.apache.org/security/vulnerabilities_13.html
- GLSA-200711-06 vendor-advisory
- 28224 third-party-advisory
- 200032 vendor-advisory
- 25830 third-party-advisory
- 24215 vdb-entry
- http://support.avaya.com/elmodocs2/security/ASA-2007-363.htm
- USN-499-1 vendor-advisory
- RHSA-2008:0261 vendor-advisory
- 26508 third-party-advisory
- http://support.avaya.com/elmodocs2/security/ASA-2007-353.htm