CVE-2026-46243: Input Validation Flaw (CVSS 7.1)

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.

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CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0035

Probability of exploitation

0.27%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

References

Other References

https://git.kernel.org/stable/c/0aece6685fc80a8de492688ca2315fb86ec379c7 https://git.kernel.org/stable/c/2035acfb17221729b1b8ac335e941868a04ca079 https://git.kernel.org/stable/c/3da1fdf4efbc490041eb4f836bf596201203f8f2 https://git.kernel.org/stable/c/7713bd320ed4fc3d08a227cd8e41242219a16981 https://git.kernel.org/stable/c/91f89c1d83e80417629791fcef6af8140d7d01c8 https://git.kernel.org/stable/c/9544559e59438a4b609b2fdfa0763d8360572824 https://git.kernel.org/stable/c/a3bbda6502a9398b816fa2e71c9a3f955f58013d https://git.kernel.org/stable/c/cf20038657d6d4974349556a34e08fe0490bebbc http://www.openwall.com/lists/oss-security/2026/06/01/6 https://github.com/manizada/CIFSwitch

Frequently Asked Questions

What is CVE-2026-46243? +

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. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-46243? +

CVE-2026-46243 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0035, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-46243? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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