What is CVE-2026-63994?

CVE-2026-63994 is a unscored severity Linux kernel vulnerability, affecting Linux kernel versions from 5.9 onward and patched in 5.10.259, 5.15.210, 6.1.176 and others. CVE-2026-63994 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-63994?

CVE-2026-63994 has a CVSS score of pending NVD analysis out of 10, rated awaiting scoring severity.

Is there a patch available for CVE-2026-63994?

Yes, CVE-2026-63994 has been patched. Fixed versions include 5.10.259, 5.15.210, 6.1.176 and others. If you are running Linux kernel 5.9 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-63994 actively exploited?

CVE-2026-63994 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-63994

In the Linux kernel, the following vulnerability has been resolved: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head. Fix this possible UAF by initializing the local variables after the skb_cow() call. Remove skb_reset_network_header() calls which were not needed.

Package Linux Kernel

Published 2026-07-19

Last modified 2026-07-19

Patch available

Yes

Affected versions

Linux kernel versions 5.9 and later are affected. Fixed in 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1 and their respective stable series.

Affected from

≥ 5.9

Fixed in

✓ 5.10.259 5.10.x ✓ 5.15.210 5.15.x ✓ 6.1.176 6.1.x ✓ 6.6.143 6.6.x ✓ 6.12.93 6.12.x ✓ 6.18.35 6.18.x ✓ 7.0.12 7.0.x ✓ 7.1

References

8 total

Showing 5 of 8 references View all on NVD

Frequently asked questions

What is CVE-2026-63994?

CVE-2026-63994 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 5.9 onward and has been patched in 5.10.259, 5.15.210, 6.1.176 and others. CVE-2026-63994 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
Is there a patch available for CVE-2026-63994?

Yes — CVE-2026-63994 has been patched. Fixed versions include 5.10.259, 5.15.210, 6.1.176 and others. If you are running Linux kernel 5.9 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-63994 actively exploited?

No — CVE-2026-63994 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.