Kernel-level vuln in the Linux kernel—a ubiquitous component. High CVSS (9.8) enabling kernel crash or local privilege escalation; broad impact across servers and devices.
CVE-2026-63979
Linux kernel use-after-free in net/handshake allowing kernel crash or local privilege escalation
Is CVE-2026-63979 being exploited?
Not confirmed. CVE-2026-63979 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.61% probability of exploitation in the next 30 days.
How severe is CVE-2026-63979?
CVE-2026-63979 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-63979?
Yes. A fix has been recorded for CVE-2026-63979. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63979 affect?
CVE-2026-63979 affects Linux kernel (net/handshake subsystem), Linux-based servers, appliances, containers, embedded devices using upstream kernel. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63979?
Install vendor/kernel security updates and reboot affected hosts immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Local attacker can induce use-after-free/dereference of freed socket file, causing kernel crash or potential local privilege escalation (kernel compromise/RCE).
Immediate action required
- affected>= 3b3009ea8abb713b022d94fba95ec270cf6e7eae and < 68eba6519cbd6359fb554a9720f3a3b6b2eba23f
- affected>= 3b3009ea8abb713b022d94fba95ec270cf6e7eae and < c06876d4fac38f35820946ee3b1be7d7da799cd4
- affected>= 3b3009ea8abb713b022d94fba95ec270cf6e7eae and < f4251190e58b209999c1ba9e6d2976136a1be055
- affected6.4
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.