9.8

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

Modified
AliasesUBUNTU-CVE-2026-64136DEBIAN-CVE-2026-64136
Published 19-07-2026Last modified 30-10-2026

Vulnerability summary

CVE-2026-64136 is a critical (CVSS 9.8) vulnerability in linux. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 35% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.41%
0%100%
Low · -0.26 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 24 · Related 22
RHSA-2026:61887RHSA-2026:64808SUSE-SU-2026:4120-1SUSE-SU-2026:4254-1USN-8593-1USN-8603-1

Timeline

  1. 19-07-2026
    PublishedVulnerability first disclosed.
  2. 30-10-2026
    Last modifiedVulnerability information updated.

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 metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.41%

Chance of exploitation in the next 30 days

Percentile

35%

Versus all other CVEs

30-day change

Decrease -0.26 pp

From 0.67% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu133 products
  • linux< 6.8.0-139.139 | < 7.0.0-28.28
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.8.0-1064.67 | < 7.0.0-1009.9
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 92d197ef7e9bb4994dae2bb17c2f19fa09d219a2, < 7585d4242f59185b084957fa077396e53dbf7c24 | ≥ 953953abb66e52c224057ab91e404284fefeab62, < 7df1df6f40c0720d30206aa35c0343b962350e0d | ≥ 601dd3b79769b38d30b693c40afdb2a4b7edf9d0, < 13fb413ae22a37c69341918a6d651d19a9b0b9b7 | ≥ 3969db6b22e3d90d8c5f22ac1a7fe0350a94c136, < bf4ebdb19ff9b3cdf992b50715fe61633327416a | ≥ 96c4af418586ee9a6aab61738644366426e05316, < e374f4e496fef8168784f93a4477d67be34485fd | ≥ 96c4af418586ee9a6aab61738644366426e05316, < 4d8690dace005a38e6dbde9ecce2da3ad85c7c41 | 8c59eeeeffa1524ef57e173a89a1a3ff539888d5 | ≥ 6.6.128, < 6.6.142 | ≥ 6.12.75, < 6.12.92 | ≥ 6.18.16, < 6.18.34 | ≥ 6.19.6, < 6.20 | 7.0
  • linux_kernel≥ 6.6.128, < 6.6.142 | ≥ 6.12.75, < 6.12.92 | ≥ 6.18.16, < 6.18.34 | ≥ 6.19.6, < 7.0.11 | 7.1:rc1 | 7.1:rc2 | 7.1:rc3 | 7.1:rc4
Debian1 product
  • linux< 6.12.94-1 | < 7.0.12-1

3 vendors · 136 products

References

30 links
Show all 30 references