CVE-2026-31409: ksmbd: unset conn->binding on failed binding request

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-06 · updated 2026-07-24

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: unset conn->binding on failed binding request When a multichannel SMB2_SESSION_SETUP request with SMB2_SESSION_REQ_FLAG_BINDING fails ksmbd sets conn->binding = true but never clears it on the error path. This leaves the connection in a binding state where all subsequent ksmbd_session_lookup_all() calls fall back to the global sessions table. This fix it by clearing conn->binding = false in the error path.

Affected products

Linux kernel: from 5.15 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.20; from 6.19 before 6.19.10; 7.0-rc1, 7.0-rc2, 7.0-rc3, 7.0-rc4 — fixed in 6.1.167, 6.12.78, 6.18.20, 6.19.10, 6.6.130

How to fix

Upgrade to a fixed version: Linux kernel 6.1.167, 6.12.78, 6.18.20, 6.19.10. Check the vendor advisory for mitigations.

References

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