Affects widely used Linux kernel; core infrastructure; privilege escalation risk; patch available.
CVE-2026-43391
Linux kernel NSFS patch fixes namespace permission leakage
Is CVE-2026-43391 being exploited?
Not confirmed. CVE-2026-43391 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.13% probability of exploitation in the next 30 days.
How severe is CVE-2026-43391?
CVE-2026-43391 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-43391?
Yes. A fix has been recorded for CVE-2026-43391. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-43391 affect?
CVE-2026-43391 affects Linux kernel. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-43391?
Apply kernel patch and reboot
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Privilege escalation via namespace visibility between privileged services; potential information leakage.
Patch when possible
- affected>= 5222470b2fbb3740f931f189db33dd1367b1ae75 and < 24ebaf6676ae4f74f4856eb645959b15e62bc1b4
- affected>= 5222470b2fbb3740f931f189db33dd1367b1ae75 and < 1797ee11451f1b2be69863a9f5bd43b948813fdf
- affected>= 5222470b2fbb3740f931f189db33dd1367b1ae75 and < d2324a9317f00013facb0ba00b00440e19d2af5e
- affected6.18
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.