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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于smb2_find_smb_sess_tcon_unlocked()函数中tc_count增量缺少锁定保护。

CVSS 9.8 · Critical EPSS 0.49% · P41

Possible ATT&CK Techniques 1 AI

T1205.001 · Port Knocking

Affected Version Matrix 17

VendorProduct Version RangeStatus
Linux Linux 953953abb66e52c224057ab91e404284fefeab62< 7df1df6f40c0720d30206aa35c0343b962350e0d affected
601dd3b79769b38d30b693c40afdb2a4b7edf9d0< 13fb413ae22a37c69341918a6d651d19a9b0b9b7 affected
3969db6b22e3d90d8c5f22ac1a7fe0350a94c136< bf4ebdb19ff9b3cdf992b50715fe61633327416a affected
96c4af418586ee9a6aab61738644366426e05316< e374f4e496fef8168784f93a4477d67be34485fd affected
96c4af418586ee9a6aab61738644366426e05316< 4d8690dace005a38e6dbde9ecce2da3ad85c7c41 affected
8c59eeeeffa1524ef57e173a89a1a3ff539888d5 affected
6.6.128< 6.6.142 affected
6.12.75< 6.12.92 affected
… +9 more rows
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I. Basic Information for CVE-2026-64136

Vulnerability Information
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Vulnerability Title
smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
Source: CVE Program / CVE List V5
Vulnerability 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().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于smb2_find_smb_sess_tcon_unlocked()函数中tc_count增量缺少锁定保护。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 953953abb66e52c224057ab91e404284fefeab62 ~ 7df1df6f40c0720d30206aa35c0343b962350e0d -
Linux Linux 7.0 -

II. Public POCs for CVE-2026-64136

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III. Intelligence Information for CVE-2026-64136

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Patches & Fixes for CVE-2026-64136 (4)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-53399 9.8 CRITICAL nfsd: release layout stid on setlease failure
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-63886 9.8 CRITICAL scsi: target: iscsi: Validate CHAP_R length before base64 decode
CVE-2026-63924 9.8 CRITICAL ipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64066 9.8 CRITICAL netfs: Fix netfs_read_to_pagecache() to pause on subreq failure
CVE-2026-64061 9.8 CRITICAL netfs: Fix early put of sink folio in netfs_read_gaps()
CVE-2026-64056 9.8 CRITICAL net: ethernet: cortina: Make RX SKB per-port
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-64055 9.8 CRITICAL net: ethernet: cortina: Carry over frag counter
CVE-2026-64102 9.8 CRITICAL RDMA/siw: Reject MPA FPDU length underflow before signed receive math
CVE-2026-64046 9.8 CRITICAL net: tls: prevent chain-after-chain in plain text SG
CVE-2026-63825 9.8 CRITICAL gcov: use atomic counter updates to fix concurrent access crashes
CVE-2026-64122 9.8 CRITICAL net/mlx5e: Fix use-after-free in mlx5e_tx_reporter_timeout_recover
CVE-2026-64035 9.8 CRITICAL igc: set tx buffer type for SMD frames
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64136

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