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

Q: How do I fix CVE-2026-57589?

openbsd: upgrade to newer than 7.9. Exact commands for each OS are on this page.

Q: Is CVE-2026-57589 being exploited?

CVE-2026-57589 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-57589 affect?

CVE-2026-57589 affects openbsd. Severity is high (CVSS 7.4). 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().

Routine

HIGH 7.4UPGRADE

CVE-2026-57589 is a high-severity flaw (CVSS 7.4) affecting openbsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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().

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.4 (High)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-06-25
Last modified	2026-07-10

Publisher (CNA): MITRE · Vendor: openbsd

Last updated 2026-07-10 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-25 01:16 UTCPublished CVE record published
2026-07-10 16:39 UTCUpdated Record last modified

openbsd openbsd UPGRADE

Affected: <= 7.9

Fixed in: newer than 7.9

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-57589?

openbsd: upgrade to newer than 7.9. Exact commands for each OS are on this page.

Is CVE-2026-57589 being exploited?

CVE-2026-57589 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-57589 affect?

CVE-2026-57589 affects openbsd. Severity is high (CVSS 7.4). 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().

How urgent is CVE-2026-57589?

Priority 27/100. High severity

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References

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