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Advisory severityHigh7.0Vendor: MediumRed Hat Linux

High [CVE-2026-64523] Take a long-lived file reference at submit

This high-severity Red Hat Linux advisory covers CVE-2026-64523 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.

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CVE-2026-64523 Source published Source updated

VulniPulse record published Record updated

CVE-2026-64523
Affected products & platforms
Red Hat LinuxLinux Kernel
Open source advisory

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Summary

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.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · medium-confidence parse· fetched 26 days ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.

Official advisory · medium-confidence parse· fetched 26 days ago·verify at source

Mitigation

The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.

Official advisory · medium-confidence parse· fetched 26 days ago·verify at source

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