CVE-2026-46243: smb: client: reject userspace cifs.spnego descriptions
cifs.spnego key descriptions contain authority-bearing fields such as pid, uid, creduid, and upcalltarget that cifs.upcall treats as kernel-originating inputs. However, userspace can also create keys of this type through requestkey(2) or addkey(2), allowing those fields to be supplied without CIFS origin. Only accept cifs.spnego descriptions while CIFS is using its private spnegocred to request the key.
Other sources
smb: client: reject userspace cifs.spnego descriptions
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.6.143.1-1 - Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.262-1Fixed in 6.1.176-1Fixed in 6.1.180-1Fixed in 6.12.94-1Fixed in 6.12.101-1Fixed in 7.1.8-1Fixed in 7.1.8-2
Event History
Frequently Asked Questions
What is the severity of CVE-2026-46243?
The severity of CVE-2026-46243 is high with a CVSS score of 7.8.
How do I fix CVE-2026-46243?
To fix CVE-2026-46243, update your Linux kernel to the latest version that includes the patch addressing this vulnerability.
What type of vulnerability is CVE-2026-46243?
CVE-2026-46243 is an input validation vulnerability within the cifs module of the Linux kernel.
What impact does CVE-2026-46243 have on systems?
CVE-2026-46243 can potentially allow unauthorized access to sensitive information due to improper handling of inputs.
On which software does CVE-2026-46243 affect?
CVE-2026-46243 affects the Linux kernel specifically related to the cifs protocol.