CVE-2026-89538 Linux kernel - Authentication Bypass

Linux kernel contains a broken authentication vulnerability in SUNRPC where oversized Kerberos v2 wrap tokens with invalid ec field are not properly rejected, letting attackers with valid GSS context cause semantic buffer inconsistencies, exploit requires valid GSS context.

CVSS base score 9.8 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.71% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
11 September 2026
Updated
15 October 2026

Vendor fix

Update to the latest Linux kernel version containing the fix.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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