CVE-2026-64136 smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()

What is CVE-2026-64136?

CVE-2026-64136 is a critical vulnerability in Linux kernel, published on 19 Jul 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:

smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()

Commit 96c4af418586 ("cifs: Fix locking usage for tcon fields") refactored cifs code to change cifs_tcp_ses_lock for tc_lock around tc_count changes.

There was missing lock around tc_count increment inside smb2_find_smb_sess_tcon_unlocked().

Weakness: CWE-362

Which versions are affected by CVE-2026-64136?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64136?

Apply the vendor's patch.

Is CVE-2026-64136 being exploited?

There is no known exploitation of CVE-2026-64136 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-64136, DEBIAN-CVE-2026-64136, GHSA-6vvf-f9vp-vcgv, UBUNTU-CVE-2026-64136.