The clone system call in the Linux kernel 2.6.28 and earlier allows local users to send arbitrary signals to a parent process from an unprivileged child process by launching an additional child process with the CLONE_PARENT flag, and then letting this new process exit.
lists.opensuse.org/opensuse-security-announce/2009-02/msg00003.html
lists.opensuse.org/opensuse-security-announce/2009-06/msg00000.html
lists.opensuse.org/opensuse-security-announce/2009-06/msg00001.html
osvdb.org/52204
rhn.redhat.com/errata/RHSA-2009-0459.html
scary.beasts.org/security/CESA-2009-002.html
scarybeastsecurity.blogspot.com/2009/02/linux-kernel-minor-signal-vulnerability.html
secunia.com/advisories/33758
secunia.com/advisories/34033
secunia.com/advisories/34680
secunia.com/advisories/34917
secunia.com/advisories/34962
secunia.com/advisories/34981
secunia.com/advisories/35011
secunia.com/advisories/35120
secunia.com/advisories/35121
secunia.com/advisories/35390
secunia.com/advisories/35394
secunia.com/advisories/37471
wiki.rpath.com/Advisories:rPSA-2009-0084
www.debian.org/security/2009/dsa-1787
www.debian.org/security/2009/dsa-1794
www.debian.org/security/2009/dsa-1800
www.mandriva.com/security/advisories?name=MDVSA-2009:118
www.redhat.com/support/errata/RHSA-2009-0326.html
www.redhat.com/support/errata/RHSA-2009-0451.html
www.securityfocus.com/archive/1/503610/100/0/threaded
www.securityfocus.com/archive/1/507985/100/0/threaded
www.securityfocus.com/bid/33906
www.ubuntu.com/usn/usn-751-1
www.vmware.com/security/advisories/VMSA-2009-0016.html
www.vupen.com/english/advisories/2009/3316
bugzilla.redhat.com/show_bug.cgi?id=479932
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11187
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7947