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.

CVSS 3.1

9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

0.5% chance of exploitation in the next 30 days; higher than 43% of CVEs (scores of 2026-10-25)

CWE

CWE-416

Published

2026-07-19

Modified

2026-10-19

Record from

the NVD, synced 2026-10-21

Affected

• linux:linux_kernel

References

• https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11
• https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7
• https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b
• https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934
• https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4

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