{"id":"CVE-2026-99041","summary":"ip6_gre: remove obsolete ERSPAN PMTU update","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nip6_gre: remove obsolete ERSPAN PMTU update\n\nA tc tunnel_key action can attach a METADATA_IP_TUNNEL dst to an skb,\nand mirred can redirect it to a native ip6erspan device. The legacy PMTU\nupdate in ip6erspan_tunnel_xmit() treats that metadata dst as a route.\nSince it has no output device, dst_dev(dst)-\u003emtu dereferences NULL.\n\nOn v7.2 with KASAN, an initial UID/GID 65534 process with CapEff 0 used\nself-created user and network namespaces to trigger:\n\n  KASAN: null-ptr-deref\n  RIP: ip6erspan_tunnel_xmit+0x10fc/0x2cc0\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nThe update is obsolete. Commit fe1a4ca0a2b7 (\"ip6_gre: process toobig\nin a better way\") changed IPv6 GRE Too Big handling to update the\nunderlay route and removed the equivalent block from __gre6_xmit().\nip6_tnl_xmit() then propagates the underlay PMTU to the overlay route.\n\nRemove the stale ERSPAN copy and its now-unused dst variable. This\neliminates the metadata-dst dereference and keeps ERSPAN aligned with\nIPv6 GRE PMTU handling.","modified":"2026-11-01T02:37:55.018596797Z","published":"2026-10-23T12:22:00.403Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99041.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2d06cb25a497d3a7034ef9d172626c2d6620a0f1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2e151c74bcc53e3ed313bd1c21b0d5bb442edbc0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8bc60db48e8cba35488bbd6e1f94aa990afa275a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8f27260b989f488760289276377db24fbfb20bfa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b14a682ad7d45345701e08f9279d483a1da8b36c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ba72ed1c8476ce68eb7152dfcbc5330cefcbaa91"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f5b143f4cd3fb7673df8d727550478a4b762908a"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99041.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99041"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5a963eb61b7c39e6c422b6e48619d19d04719358"},{"fixed":"2e151c74bcc53e3ed313bd1c21b0d5bb442edbc0"},{"fixed":"ba72ed1c8476ce68eb7152dfcbc5330cefcbaa91"},{"fixed":"b14a682ad7d45345701e08f9279d483a1da8b36c"},{"fixed":"f5b143f4cd3fb7673df8d727550478a4b762908a"},{"fixed":"2d06cb25a497d3a7034ef9d172626c2d6620a0f1"},{"fixed":"8f27260b989f488760289276377db24fbfb20bfa"},{"fixed":"8bc60db48e8cba35488bbd6e1f94aa990afa275a"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99041.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.16.0"},{"fixed":"5.15.224"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.191"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.160"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.114"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.58"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99041.json"}}],"schema_version":"1.9.2"}