Affects the Linux kernel; enables local privilege escalation and host crash across container hosts and cloud instances—widely deployed and high-impact.
CVE-2026-63917
Linux kernel vti6 netns bug enables local privilege escalation and kernel crash
Is CVE-2026-63917 being exploited?
Not confirmed. CVE-2026-63917 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 0.17% probability of exploitation in the next 30 days.
How severe is CVE-2026-63917?
CVE-2026-63917 is rated High with a CVSS score of 8.8. 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-2026-63917?
Yes. A fix has been recorded for CVE-2026-63917. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63917 affect?
CVE-2026-63917 affects Linux kernel (vti6 tunnel/netns), Container hosts / VMs, Unprivileged user namespaces, Cloud/container platforms. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63917?
Apply vendor/kernel security updates or backports immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unprivileged user-namespace attacker can trigger a kernel BUG/use-after-free, enabling local privilege escalation or host denial-of-service across containers.
Immediate action required
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < 0cdce7618464f7fb06f461e8f4ad575cb1d570f4
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < f5c68875e25f331e497ddfbe81e2d8163a87f136
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < d9c5eecdb3c740e65038651db7c686b10d76d1bc
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < f1e89a943ee574d0f2f16246eb3f2d7330fdeb03
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < 225b467e3b631f38be22e4b38062a1fed02fdd21
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < fc32be9ac2788524c6b24efd681cce7a6e731a92
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < ee1778ba0f5cb53be771f97017d01eb356c797bf
- affected>= 61220ab349485d911083d0b7990ccd3db6c63297 and < 11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe
- affected3.15
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.