tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()

These records connect through source-stated identifiers. Shared identifiers or dates alone do not establish shared exposure, root cause or applicability.

CVE-2026-63992 · Microsoft / collected KEV context

cve-program · CVE-2026-63992

• https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c
• https://git.kernel.org/stable/c/c7b7ec3e69e673c0d6b57f74d21da50c485c598e
• https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4
• https://git.kernel.org/stable/c/e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec
• https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7
• https://git.kernel.org/stable/c/43368636c663cff6e59dde93cf4b8e43ac28eb93
• https://git.kernel.org/stable/c/cb549df9ce4ee15c9d5b19ddab12cf2128e4313c
• https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d

No related operational record is retained in the current change model.