CVE-2026-63992

In the Linux kernel, the following vulnerability has been resolved: tunnels: do not assume transport header in iptunnel_pmtud_check_icmp() In some cases, iptunnel_pmtud_check_icmp() can be called while skb transport header is not set. This triggers an out-of-bound access, because (typeof(skb->transport_header))~0U is 65535. Access the icmp header based on IPv4 network header, after making sure icmp->type is present in skb linear part. Note that iptunnel_pmtud_check_icmpv6()) is fine.

CVSS 3.1

9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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-125

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/43368636c663cff6e59dde93cf4b8e43ac28eb93
• https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d
• https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c
• https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4
• https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7

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