CVE-2026-98175: smb: client: cancel reconnect work in clean_demultiplex_info()

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% 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: 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.

Affected products

Linux kernel: from 3.10.107 before 3.11; from 3.12.70 before 3.13; from 3.16.42 before 3.17; from 3.18.47 before 3.19; from 4.1.38 before 4.2; from 4.4.40 before 4.5 — fixed in 3.11, 3.13, 3.17, 3.19, 4.10, 4.2

How to fix

Upgrade to a fixed version: Linux kernel 3.11, 3.13, 3.17, 3.19. Check the vendor advisory for mitigations.

References

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