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

mediumCVSS 5.5CVE-2026-64523

CSIRTS triage

vendor: Linux product: kernelOther

What: A long-lived file reference is taken at submission in the handshake process.
Who is affected: Deployments of the Linux kernel with networking capabilities may be affected.
Urgency: Remediation is advisable to ensure proper resource management, though exploitation is not currently known.
Action: Monitor for updates regarding this issue.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64523

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-645230.35% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 27% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-64523	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for net/handshake

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

criticalCVE-2026-64523: In the Linux kernel, the following vulnerability has been resolved: net/handshake: Take a long…nvd · 2026-07-25
highCVE-2026-63980: In the Linux kernel, the following vulnerability has been resolved: net/handshake: Use spin_lo…nvd · 2026-07-19
criticalCVE-2026-63979: In the Linux kernel, the following vulnerability has been resolved: net/handshake: hand off th…nvd · 2026-07-19
criticalCVE-2026-63978: In the Linux kernel, the following vulnerability has been resolved: net/handshake: Drain pendi…nvd · 2026-07-19
criticalCVE-2026-63979: net/handshake: hand off the pinned file reference to accept_doitmsrc · 2026-07-14
highCVE-2026-63978: net/handshake: Drain pending requests at net namespace exitmsrc · 2026-07-14