Linux kernel is ubiquitous across servers, cloud, routers and endpoints; a remote, unauthenticated network-triggered kernel use-after-free can crash systems or enable RCE, causing broad disruption.
CVE-2026-74478
Linux kernel use-after-free in vector_mmsg_rx allows remote crash or RCE.
Is CVE-2026-74478 being exploited?
Not confirmed. CVE-2026-74478 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 0.57% probability of exploitation in the next 30 days.
How severe is CVE-2026-74478?
CVE-2026-74478 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-2026-74478?
Yes. A fix has been recorded for CVE-2026-74478. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-74478 affect?
CVE-2026-74478 affects Linux kernel (vector_mmsg_rx networking subsystem), Systems using GRE or L2TPv3 transports, Servers, routers, cloud instances running vulnerable kernels. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-74478?
Install vendor kernel updates or backported fixes and block untrusted GRE/L2TPv3 peers.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker on GRE/L2TPv3 can trigger a use-after-free, causing kernel crash or potential arbitrary code execution and root privilege escalation.
Immediate action required
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < 967c779c9853d2a1cc9cd8e61d300250c348f3d9
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < a7bc015bb798c525e7a82dd14225c6aeb994274b
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < 7dc9781e320d664c9bdd50003c9acfddf363d1e1
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < 4b9601595e8b6b5d18878cac0aeabc687d241111
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < 67d58ab4f2ccf7145f3da07e025735a09c79de1b
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < 180ff4c81faf01ec4e06082c9daa7c40518ead89
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < 804b681002ead233abf49a3efd681f5468a835f9
- affected>= 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and < af421e9aed3920c7ac88c24daa48606c7112feca
- affected4.17
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.