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CVE-2026-64523— net/handshake: Take a long-lived file reference at submit

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 6.4版本存在安全漏洞，该漏洞源于net/handshake模块文件引用管理不当，可能导致socket被过早释放，造成系统崩溃或拒绝服务。

CVSS 9.8 · Critical EPSS 0.67% · P51

Possible ATT&CK Techniques 1 AI

T1564.004 · NTFS File Attributes

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 3b3009ea8abb713b022d94fba95ec270cf6e7eae< 685b10dd0e32c7782cead16c8cf055c609678583 affected
3b3009ea8abb713b022d94fba95ec270cf6e7eae< b913801ad9b9a51437d84d030ec6843e08976bd6 affected
3b3009ea8abb713b022d94fba95ec270cf6e7eae< 16eaba5aa89c04eea125905bb8f988c1897f4f29 affected
3b3009ea8abb713b022d94fba95ec270cf6e7eae< 09dba37eee70d0596e26645015f1aa95a9848e9d affected
6.4 affected
< 6.4 unaffected
6.12.93≤ 6.12.* unaffected
6.18.44≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-64523

Vulnerability Information
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Vulnerability Title
net/handshake: Take a long-lived file reference at submit
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/handshake: Take a long-lived file reference at submit handshake_nl_accept_doit() needs the file pointer backing req->hr_sk->sk_socket to survive the window between handshake_req_next() and the subsequent FD_PREPARE() and get_file(). The submit-side sock_hold() does not provide that. sk_refcnt keeps struct sock alive, but struct socket is owned by sock->file: when the consumer fputs the last file reference, sock_release() tears the socket down regardless of any sock_hold. Add an hr_file pointer to struct handshake_req and acquire an explicit reference on sock->file during handshake_req_submit(). handshake_complete() and handshake_req_cancel() release the reference on the completion-bit-winning path. The submit error path must also release the file reference, but after rhashtable insertion a concurrent handshake_req_cancel() can discover the request and race the error path. Gate the error-path cleanup -- sk_destruct restoration, fput, and request destruction -- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same serialization handshake_complete() and handshake_req_cancel() already use. When cancel has already claimed ownership, the submit error path returns without touching the request; socket teardown handles final destruction. The accept-side dereferences are not yet retargeted; that change comes in the next patch.
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 6.4版本存在安全漏洞，该漏洞源于net/handshake模块文件引用管理不当，可能导致socket被过早释放，造成系统崩溃或拒绝服务。
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 3b3009ea8abb713b022d94fba95ec270cf6e7eae ~ 685b10dd0e32c7782cead16c8cf055c609678583 -
Linux Linux 6.4 -

II. Public POCs for CVE-2026-64523

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III. Intelligence Information for CVE-2026-64523

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Patches & Fixes for CVE-2026-64523 (3)

Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total

CVE-2026-64355 9.8 CRITICAL bpf: Reject fragmented frames in devmap
CVE-2026-64410 9.8 CRITICAL netfilter: flowtable: IPIP tunnel hardware offload is not yet support
CVE-2026-64399 9.8 CRITICAL ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
CVE-2026-64397 9.8 CRITICAL ksmbd: serialize QUERY_DIRECTORY requests per file
CVE-2026-64459 9.8 CRITICAL tcp: restore RCU grace period in tcp_ao_destroy_sock
CVE-2026-64391 9.8 CRITICAL ksmbd: use opener credentials for ADS I/O
CVE-2026-64303 9.8 CRITICAL spi: fsl-lpspi: terminate the RX channel on TX prepare failure path
CVE-2026-64439 9.8 CRITICAL crypto: krb5 - filter out async aead implementations at alloc
CVE-2026-64387 9.8 CRITICAL smb: client: fix query directory replay double-free
CVE-2026-64386 9.8 CRITICAL smb: client: fix query_info() replay double-free
CVE-2026-64385 9.8 CRITICAL smb: client: fix double-free in SMB2_ioctl() replay
CVE-2026-64383 9.8 CRITICAL smb: client: fix double-free in SMB2_flush() replay
CVE-2026-64384 9.8 CRITICAL smb: client: fix change notify replay double-free
CVE-2026-64268 9.8 CRITICAL RDMA/siw: bound Read Response placement to the RREAD length
CVE-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64320 9.1 CRITICAL nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page
CVE-2026-64392 9.1 CRITICAL ksmbd: use opener credentials for delete-on-close
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials
CVE-2026-64319 9.1 CRITICAL nvmet-auth: validate reply message payload bounds against transfer length
CVE-2026-64257 9.1 CRITICAL smb: client: reject overlapping data areas in SMB2 responses

Showing top 20 of 274 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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