{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31700","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-03-09T15:48:24.132Z","datePublished":"2026-05-01T13:56:00.205Z","dateUpdated":"2026-05-11T22:14:02.576Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-11T22:14:02.576Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd()\n\nIn tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points\ndirectly into the mmap'd TX ring buffer shared with userspace. The\nkernel validates the header via __packet_snd_vnet_parse() but then\nre-reads all fields later in virtio_net_hdr_to_skb(). A concurrent\nuserspace thread can modify the vnet_hdr fields between validation\nand use, bypassing all safety checks.\n\nThe non-TPACKET path (packet_snd()) already correctly copies vnet_hdr\nto a stack-local variable. All other vnet_hdr consumers in the kernel\n(tun.c, tap.c, virtio_net.c) also use stack copies. The TPACKET TX\npath is the only caller of virtio_net_hdr_to_skb() that reads directly\nfrom user-controlled shared memory.\n\nFix this by copying vnet_hdr from the mmap'd ring buffer to a\nstack-local variable before validation and use, consistent with the\napproach used in packet_snd() and all other callers."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"}}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/packet/af_packet.c"],"versions":[{"version":"1d036d25e5609ba73fee6a88db01c306b140d512","lessThan":"74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121","status":"affected","versionType":"git"},{"version":"1d036d25e5609ba73fee6a88db01c306b140d512","lessThan":"3a1bf9116ea31470b89692585c3910dfe830dcdd","status":"affected","versionType":"git"},{"version":"1d036d25e5609ba73fee6a88db01c306b140d512","lessThan":"28324a3b62d9ce7f9bdd65a8ce63f382041d1b27","status":"affected","versionType":"git"},{"version":"1d036d25e5609ba73fee6a88db01c306b140d512","lessThan":"48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b","status":"affected","versionType":"git"},{"version":"1d036d25e5609ba73fee6a88db01c306b140d512","lessThan":"2c054e17d9d41f1020376806c7f750834ced4dc5","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/packet/af_packet.c"],"versions":[{"version":"4.6","status":"affected"},{"version":"0","lessThan":"4.6","status":"unaffected","versionType":"semver"},{"version":"6.6.136","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.84","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.25","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.2","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.6.136"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.12.84"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.18.25"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"7.0.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"7.1-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121"},{"url":"https://git.kernel.org/stable/c/3a1bf9116ea31470b89692585c3910dfe830dcdd"},{"url":"https://git.kernel.org/stable/c/28324a3b62d9ce7f9bdd65a8ce63f382041d1b27"},{"url":"https://git.kernel.org/stable/c/48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b"},{"url":"https://git.kernel.org/stable/c/2c054e17d9d41f1020376806c7f750834ced4dc5"}],"title":"net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd()","x_generator":{"engine":"bippy-1.2.0"}}}}