In the Linux kernel, the following vulnerability has been resolved: smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()… (CVE-2026-64136)
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().
AI Analysis
Technical Summary
The Linux kernel contained a concurrency vulnerability in the SMB client implementation where the tc_count variable was incremented without proper locking in the smb2_find_smb_sess_tcon_unlocked() function. This missing lock could cause race conditions affecting the integrity of the tc_count state. The vulnerability was addressed by commit 96c4af418586, which refactored the locking scheme to use tc_lock around tc_count modifications, replacing the previous cifs_tcp_ses_lock usage.
Potential Impact
The vulnerability could lead to race conditions in the SMB client code, potentially causing inconsistent or corrupted state related to SMB session connections. No known exploits in the wild have been reported. The impact is limited to concurrency issues within the kernel SMB client subsystem.
Mitigation Recommendations
A fix has been committed to the Linux kernel source code (commit 96c4af418586) that properly protects the tc_count increment with locking. Users should apply the updated kernel version containing this fix once it is released. Patch status is not explicitly confirmed in the provided data; check the Linux kernel vendor advisory or source repository for the exact fixed versions and update accordingly.
In the Linux kernel, the following vulnerability has been resolved: smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()… (CVE-2026-64136)
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().
CVSS v3.1
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel contained a concurrency vulnerability in the SMB client implementation where the tc_count variable was incremented without proper locking in the smb2_find_smb_sess_tcon_unlocked() function. This missing lock could cause race conditions affecting the integrity of the tc_count state. The vulnerability was addressed by commit 96c4af418586, which refactored the locking scheme to use tc_lock around tc_count modifications, replacing the previous cifs_tcp_ses_lock usage.
Potential Impact
The vulnerability could lead to race conditions in the SMB client code, potentially causing inconsistent or corrupted state related to SMB session connections. No known exploits in the wild have been reported. The impact is limited to concurrency issues within the kernel SMB client subsystem.
Mitigation Recommendations
A fix has been committed to the Linux kernel source code (commit 96c4af418586) that properly protects the tc_count increment with locking. Users should apply the updated kernel version containing this fix once it is released. Patch status is not explicitly confirmed in the provided data; check the Linux kernel vendor advisory or source repository for the exact fixed versions and update accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-6vvf-f9vp-vcgv
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64136"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27a82a4a8d598912af21
Added to database: 07/19/2026, 19:38:16 UTC
Last enriched: 07/19/2026, 19:45:52 UTC
Last updated: 07/20/2026, 19:41:21 UTC
Views: 12
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