CVE-2026-98261 cifs: Fix server use-after-free in cifs_chan_skip_or_disable()
A use-after-free in the Linux kernel CIFS module allows attackers to cause denial of service or execute arbitrary code via secondary channel handling.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98261?
CVE-2026-98261 is a high-severity use after free vulnerability in Linux, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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().
Which versions are affected by CVE-2026-98261?
How do I fix CVE-2026-98261?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98261 being exploited?
There is no known exploitation of CVE-2026-98261 in the wild and no public exploit code.
Sources
Also known as AZL-106014, BELL-CVE-2026-98261, DEBIAN-CVE-2026-98261, GHSA-mfc9-mfpp-wwcf, UBUNTU-CVE-2026-98261.