CVE-2026-46243 smb: client: reject userspace cifs.spnego descriptions

What is CVE-2026-46243?

CVE-2026-46243 is a high-severity vulnerability in Linux kernel, published on 1 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

smb: client: reject userspace cifs.spnego descriptions

cifs.spnego key descriptions contain authority-bearing fields such as pid, uid, creduid, and upcall_target that cifs.upcall treats as kernel-originating inputs. However, userspace can also create keys of this type through request_key(2) or add_key(2), allowing those fields to be supplied without CIFS origin.

Only accept cifs.spnego descriptions while CIFS is using its private spnego_cred to request the key.

Weakness: CWE-825, CWE-20

Which versions are affected by CVE-2026-46243?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-46243?

Apply the vendor's patch.

Is CVE-2026-46243 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46243 exists.

Public exploit code: 5 proofs of concept on GitHub.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALSA-2026:23258, ALSA-2026:23259, AZL-89309, BELL-CVE-2026-46243, DEBIAN-CVE-2026-46243, GHSA-3mg7-pfmq-9qfv and 8 more.