CVE-2026-31476

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put().

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CVSS v3.1 Score

8.2

HIGH

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

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.46%

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.

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.15.1 — 6.1.168
linux	linux_kernel	6.2 — 6.6.131
linux	linux_kernel	6.7 — 6.12.80
linux	linux_kernel	6.13 — 6.18.21
linux	linux_kernel	6.19 — 6.19.11
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/1d1888b4a7aec518b707f6eca0bf08992c0e8da3 https://git.kernel.org/stable/c/6fafc4c4238e538969f1375f9ecdc6587c53f1cc https://git.kernel.org/stable/c/9bbb19d21ded7d78645506f20d8c44895e3d0fb9 https://git.kernel.org/stable/c/a897064a457056acb976e20e3007cdf553de340f https://git.kernel.org/stable/c/e0e5edc81b241c70355217de7e120c97c3429deb https://git.kernel.org/stable/c/f5300690c23c5ac860499bb37dbc09cf43fd62e6

Frequently Asked Questions

What is CVE-2026-31476? +

In the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put(). It has a CVSS v3.1 base score of 8.2 (HIGH).

How severe is CVE-2026-31476? +

CVE-2026-31476 has a CVSS v3.1 score of 8.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-31476? +

CVE-2026-31476 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-31476? +

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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