CVE-2026-74608: smb: client: Fix use-after-free in cifs_try_adding_channels()

Severity: critical (CVSS 9.8 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: 2026-08-22 · updated 2026-10-16

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: Fix use-after-free in cifs_try_adding_channels() cifs_try_adding_channels() takes a temporary reference to an interface before dropping iface_lock. If cifs_ses_add_channel() fails, it drops that reference and then increments iface->weight_fulfilled. A concurrent interface list refresh can remove the list reference while channel creation is in progress. In that case, the failure-path kref_put() releases the last reference and frees iface. Updating weight_fulfilled afterward then accesses freed memory. Increment weight_fulfilled before dropping the temporary reference, keeping iface alive for the final access.

Affected products

Linux kernel: from 6.1.78 before 6.1.183; from 6.6.17 before 6.6.152; from 6.7.5 before 6.8; 6.8 — fixed in 6.1.183, 6.6.152, 6.8, 7.2

How to fix

Upgrade to a fixed version: Linux kernel 6.1.183, 6.6.152, 6.8, 7.2. Check the vendor advisory for mitigations.

References

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