tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()

Summary

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.

Timeline

1. Jul 19, 2026, 2:56 PM UTCCVE published
2. Oct 16, 2026, 3:34 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Oct 19, 2026, 8:18 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in 5a92cb45e34749865d03daf8d3500f77b5f6644c; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in c7b7ec3e69e673c0d6b57f74d21da50c485c598e; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in 7f4f7efe7f30edd29c4988de01728bf2398217e4; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in a096b6e34f602950af9a2b0856cd93a5f4c276d7; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in 43368636c663cff6e59dde93cf4b8e43ac28eb93; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in cb549df9ce4ee15c9d5b19ddab12cf2128e4313c; From 4cb47a8644cc9eb8ec81190a50e79e6530d0297f · fixed in 509323077ef79a26ba0c60bb556e45c12c398b2d

• Linux Linux

  5.9

• KernelLinux

  From 5.9.0 · fixed in 5.10.259; From 5.11.0 · fixed in 5.15.210; From 5.16.0 · fixed in 6.1.176; From 6.2.0 · fixed in 6.6.143; From 6.7.0 · fixed in 6.12.93; From 6.13.0 · fixed in 6.18.35; From 6.19.0 · fixed in 7.0.12

References 8