Description
The compat_alloc_user_space functions in include/asm/compat.h files in the Linux kernel before 2.6.36-rc4-git2 on 64-bit platforms do not properly allocate the userspace memory required for the 32-bit compatibility layer, which allows local users to gain privileges by leveraging the ability of the compat_mc_getsockopt function (aka the MCAST_MSFILTER getsockopt support) to control a certain length value, related to a "stack pointer underflow" issue, as exploited in the wild in September 2010.
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 | linux-2.6 | 2.6.26-25lenny1 | DSA-2110-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | perf +14 | 2.6.32-71.7.1.el6 | RHSA-2010:0842 |
| RHEL 5 | kernel +12 | 2.6.18-194.11.4.el5 | RHSA-2010:0704 |
| RHEL 4 | kernel +10 | 2.6.9-89.29.1.EL | RHSA-2010:0718 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5.4 EUS | kernel +12 | 2.6.18-164.25.2.el5 | RHSA-2010:0705 |
| RHEL 5.3 EUS | kernel +12 | 2.6.18-128.23.2.el5 | RHSA-2010:0711 |
| RHEL 4.7 EUS | kernel +10 | 2.6.9-78.0.33.EL | RHSA-2010:0719 |
| RHEL 3 ELS | kernel +8 | 2.4.21-66.EL | RHSA-2010:0882 |
| Red Hat MRG 1 | kernel-rt +9 | 2.6.24.7-169.el5rt | RHSA-2010:0758 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | kernel-source | 4.8.13-1.1 | openSUSE-SU-2024:10128-1 |
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.
Exploit-DB 1
- Linux Kernel 2.6.27 < 2.6.36 (RedHat x86-64) - 'compat' Local Privilege Escalation EDB-15024 · local · Sep 16, 2010 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 10
- RHSA-2010:0882 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2010:0842 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2010:0758 Red Hat Security Advisory: kernel-rt security and bug fix update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2010:0718 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2010:0719 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2010:0711 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2010:0704 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2010:0705 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- DSA-2110-1 linux-2.6 - several issues Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10128-1 kernel-debug-4.8.13-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- http://www.vmware.com/security/advisories/VMSA-2010-0017.html
- http://isc.sans.edu/diary.html?storyid=9574
- ADV-2010-3083 vdb-entry
- ADV-2010-3117 vdb-entry
- http://sota.gen.nz/compat1/
- MDVSA-2010:198 vendor-advisory
- https://access.redhat.com/kb/docs/DOC-40265
- 20101130 VMSA-2010-0017 VMware ESX third party update for Service Console kerne mailing-list
- 42384 third-party-advisory
- 20100916 Workaround for Ac1db1tch3z exploit. mailing-list
- SUSE-SA:2011:007 vendor-advisory
- RHSA-2010:0842 vendor-advisory
- MDVSA-2010:247 vendor-advisory
- ADV-2011-0298 vdb-entry
- RHSA-2010:0882 vendor-advisory
- http://www.kernel.org/pub/linux/kernel/v2.6/snapshots/patch-2.6.36-rc4-git2.log
- SUSE-SA:2010:050 vendor-advisory
- http://blog.ksplice.com/2010/09/cve-2010-3081/
- 43315 third-party-advisory
- SUSE-SR:2010:017 vendor-advisory
- http://www.vmware.com/security/advisories/VMSA-2011-0003.html
- 20100916 Ac1db1tch3z vs x86_64 Linux Kernel mailing-list
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=c41d68a513c71e35a14f66d71782d27a79a81ea6
- RHSA-2010:0758 vendor-advisory
- 20110211 VMSA-2011-0003 Third party component updates for VMware vCenter Server, vCenter Update Manager, ESXi and ESX mailing-list
- https://bugzilla.redhat.com/show_bug.cgi?id=634457
- MDVSA-2010:214 vendor-advisory
- [oss-security] 20100916 CVE-2010-3081 kernel: 64-bit Compatibility Mode Stack Pointer Underflow mailing-list