CVE-2026-98175 smb: client: cancel reconnect work in clean_demultiplex_info()
A use-after-free in the Linux kernel SMB client allows attackers to cause denial of service or execute code when reconnect work is queued during cleanup.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-98175?
CVE-2026-98175 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, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: cancel reconnect work in clean_demultiplex_info()
clean_demultiplex_info() cancels server->echo delayed work but not server->reconnect, which can cause a use-after-free when the demultiplex thread exits while a reconnect work is still queued:
cifs_demultiplex_thread() cifs_readv_from_socket() cifs_reconnect() __cifs_reconnect() cifs_queue_server_reconn() mod_delayed_work(cifsiod_wq, &server->reconnect, 0) clean_demultiplex_info() cancel_delayed_work_sync(&server->echo) // echo canceled // reconnect NOT canceled kfree_sensitive(server) // server freed
...later, on cifsiod_wq:
smb2_reconnect_server() server->srv_count // UAF read of freed server
Fix this by canceling server->reconnect delayed work in clean_demultiplex_info() before the server is freed, the same way cifs_put_tcp_session() already does.
Which versions are affected by CVE-2026-98175?
How do I fix CVE-2026-98175?
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-2026-98175 being exploited?
There is no known exploitation of CVE-2026-98175 in the wild and no public exploit code.
Sources
Also known as AZL-106059, BELL-CVE-2026-98175, DEBIAN-CVE-2026-98175, GHSA-22vf-w84m-jw7w, UBUNTU-CVE-2026-98175.