CVE-2026-58092: In FreeBSD 15.0, the kernel structure used to represent user credentials changed: previously the primary group

Routine

HIGH 8.1MITIGATE

CVE-2026-58092 is a high-severity flaw (CVSS 8.1) affecting freebsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In FreeBSD 15.0, the kernel structure used to represent user credentials changed: previously the primary group ID was stored in the first element of the array containing the list of supplementary group IDs, whereas now the primary group ID is stored in a dedicated field. This change was largely internal to the kernel and not user-visible. One function, group_is_primary(), was not properly updated as a part of this transition. This function is

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 72%)
CISA exploited list	No
Weakness	CWE-288
Published	2026-08-26
Last modified	2026-09-24

Publisher (CNA): FreeBSD · Vendor: freebsd

Last updated 2026-09-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-26 05:18 UTCPublished CVE record published
2026-09-24 13:34 UTCUpdated Record last modified

freebsd freebsd MITIGATE

Affected: 15.0 p1 · 15.0 p10 · 15.0 p11 · 15.0 p12 · 15.0 p2 · 15.0 p3 · 15.0 p4 · 15.0 p5

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

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-2026-58092?

freebsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-58092 being exploited?

CVE-2026-58092 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-2026-58092 affect?

CVE-2026-58092 affects freebsd. Severity is high (CVSS 8.1). In FreeBSD 15.0, the kernel structure used to represent user credentials changed: previously the primary group ID was stored in the first element of the array containing the list of supplementary group IDs, whereas now the primary group ID

How urgent is CVE-2026-58092?

Priority 35/100. High severity

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References

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