{"id":"CVE-2026-63994","title":"In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were …","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 5.9, < 5.10.259","linux_kernel >= 5.11, < 5.15.210","linux_kernel >= 5.16, < 6.1.176","linux_kernel >= 6.2, < 6.6.143","linux_kernel >= 6.7, < 6.12.93","linux_kernel >= 6.13, < 6.18.35","linux_kernel >= 6.19, < 7.0.12","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.12"],"published":"2026-07-19","updated":"2026-10-07","sourceUpdated":"2026-10-07T20:28:32.877","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63994","references":[{"url":"https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00514,"epssPercentile":0.4184,"ingestedAt":"2026-10-07T20:46:46.957Z","slug":"CVE-2026-63994","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb->head.\n\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\n\nRemove skb_reset_network_header() calls which were not needed.\n\n## Affected\n\n- `linux_kernel >= 5.9, < 5.10.259`\n- `linux_kernel >= 5.11, < 5.15.210`\n- `linux_kernel >= 5.16, < 6.1.176`\n- `linux_kernel >= 6.2, < 6.6.143`\n- `linux_kernel >= 6.7, < 6.12.93`\n- `linux_kernel >= 6.13, < 6.18.35`\n- `linux_kernel >= 6.19, < 7.0.12`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.12`","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}