CVE-2026-98261: cifs: Fix server use-after-free in cifs_chan_skip_or_disable()

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-06 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server use-after-free in cifs_chan_skip_or_disable() When a secondary channel is no longer supported by the server, cifs_chan_skip_or_disable() drops the channel reference with cifs_put_tcp_session() and then continues to use the server pointer by calling cifs_signal_cifsd_for_reconnect() on it and reading its primary_server pointer. cifs_put_tcp_session() can drop the last reference of the channel and tear it down, so both the channel and the primary server (whose reference is also dropped by cifs_put_tcp_session()) can be freed before they are signaled for reconnect. Signal the channel and the primary server and capture the primary server pointer before dropping the channel reference with cifs_put_tcp_session().

Affected products

Linux kernel: from 6.6.15 before 6.6.158; from 6.7.3 before 6.8; 6.8 — fixed in 6.6.158, 6.8, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 6.6.158, 6.8, 7.3. Check the vendor advisory for mitigations.

References

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