CVE-2026-63979: net/handshake: hand off the pinned file reference to accept_doit

criticalCVSS 9.8CVE-2026-63979

CSIRTS triage

Privilege escalation

What: This vulnerability allows for privilege escalation due to improper handling of pinned file references.
Who is affected: Deployments using the affected networking stack.
Urgency: Remediation is urgent due to the critical severity and potential for exploitation.
Action: Apply the latest patches to the networking stack.

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

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: critical — CVSS 9.8
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63979

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-2026-639790.52% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 41% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-63979	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

highUSN-8618-1: Linux kernel vulnerabilitiesubuntu
highUSN-8603-1: Linux kernel (Azure) vulnerabilitiesubuntu
highUSN-8593-1: Linux kernel vulnerabilitiesubuntu
criticalCVE-2026-63979: In the Linux kernel, the following vulnerability has been resolved: net/handshake: hand off th…nvd

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
highCVE-2026-63978: net/handshake: Drain pending requests at net namespace exitmsrc · 2026-07-14
mediumCVE-2026-64523: net/handshake: Take a long-lived file reference at submitmsrc · 2026-07-14