by Kastro
Paper/Archive/CVE-2026-63994

CVE-2026-63994

Linux Linux — tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()

EPSS 0.5%CVSS 9.8
critical.is priorityof 100
38
CVSS 9.8 (CNA)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 43.7.437 × 208.7No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 95b6d772bfe788331d9742d73eaa12e113b2adc495b6d772bfe788331d9742d73eaa12e113b2adc4CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 7254aef4d1a7e18e887af9010e2f2dc34806789b7254aef4d1a7e18e887af9010e2f2dc34806789bCNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < bf8b3f34c37c162357138e7c0942723b8b94fed1bf8b3f34c37c162357138e7c0942723b8b94fed1CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 76cd9398a0470257ab765bdf5f358a2af2e1793476cd9398a0470257ab765bdf5f358a2af2e17934CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 50750d86a2e5266aba0c295483b3397843198b1150750d86a2e5266aba0c295483b3397843198b11CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 6dff77899b9e9fe5d854abda3a98ad04e7229ef76dff77899b9e9fe5d854abda3a98ad04e7229ef7CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < f3f204541f280a6ecb04503a0d6794d93990ca43f3f204541f280a6ecb04503a0d6794d93990ca43CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < b4bc94353050b1fa7b702bd4c6600710dd926cffb4bc94353050b1fa7b702bd4c6600710dd926cffCNA
Linux5.95.10.259CNA

Scores by source

Linux (CNA)9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgit.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4refgit.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789brefgit.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1refgit.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934refgit.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11refgit.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7refgit.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43refgit.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff