CVE-2026-64136
CVE-2026-64136 is a critical-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- EPSS exploit prediction: 0% (40th percentile)
- Actively exploited: Not listed in CISA KEV
- Affected product: Linux Linux Kernel
- Published:
- Last modified:
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().
Frequently asked questions
- What is 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().
- How severe is CVE-2026-64136?
- CVE-2026-64136 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-64136 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-64136?
- CVE-2026-64136 primarily affects Linux Linux Kernel. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2026-64136?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2026-64136 published?
- CVE-2026-64136 was published on 2026-07-19 and last updated on 2026-08-13.
References
- https://git.kernel.org/stable/c/13fb413ae22a37c69341918a6d651d19a9b0b9b7
- https://git.kernel.org/stable/c/4d8690dace005a38e6dbde9ecce2da3ad85c7c41
- https://git.kernel.org/stable/c/7df1df6f40c0720d30206aa35c0343b962350e0d
- https://git.kernel.org/stable/c/bf4ebdb19ff9b3cdf992b50715fe61633327416a
- https://git.kernel.org/stable/c/e374f4e496fef8168784f93a4477d67be34485fd
Affected products (5)
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*
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