{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74478", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.903Z", "datePublished": "2026-08-15T12:27:12.549Z", "dateUpdated": "2026-08-19T16:37:30.555Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:37:30.555Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\num: vector: fix use-after-free in vector_mmsg_rx()\n\nWhen vector_mmsg_rx() discards a packet whose overlay header fails\nverify_header(), it frees the skb and continues the loop:\n\n\tif (header_check < 0) {\n\t\tdev_kfree_skb_irq(skb);\n\t\tvp->estats.rx_encaps_errors++;\n\t\tcontinue;\n\t}\n\nThe normal and short-packet paths fall through to the bottom of the\nloop body, which clears the consumed slot and advances the cursors:\n\n\t(*skbuff_vector) = NULL;\n\tmmsg_vector++;\n\tskbuff_vector++;\n\nThe verify_header() < 0 path skips that via continue, so the freed skb\nis left in skbuff_vector[] and the cursors do not advance. The next\niteration reads the same slot, gets the freed skb, and frees it again,\nproducing a refcount underflow / use-after-free in the RX path.\n\nDiscard the slot the same way the other paths do before continuing.\n\nOnly transports whose verify_header() can return negative are affected:\nGRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),\nso any peer on such a transport can trigger it without authentication." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug is reached from remotely sent GRE or L2TPv3 packets processed by vector_mmsg_rx() via recvmmsg on the tunnel socket; the fix commit states any peer on those transports can trigger it without authentication.\nAC:L - An attacker reliably triggers verify_header() failure with a wrong GRE key or L2TPv3 session/cookie, and sending two or more malformed packets in one recvmmsg batch causes immediate double-free of the same skb without races or special memory layout.\nPR:N - No privileges on the UML instance are required; exploitation needs only the ability to send network packets on the configured GRE/L2TPv3 transport, and overlay keys/cookies are not authenticated security controls.\nUI:N - Exploitation is driven entirely by remote packets delivered to the vector netdev RX path and requires no victim user or administrator action beyond the interface already being up.\nS:U - The use-after-free corrupts sk_buff memory inside the UML kernel network driver and does not by itself cross a VM, IOMMU, or host-kernel security boundary.\nC:H - The refcount underflow/use-after-free leaves a dangling sk_buff pointer that can be reallocated and read through standard heap grooming, giving an arbitrary kernel memory disclosure primitive.\nI:H - Reclaiming the freed sk_buff enables attacker-controlled contents in kernel heap objects and can be leveraged for arbitrary write or control-flow hijack in the UML kernel context.\nA:H - The double-free in the RX path can immediately oops or panic the UML kernel, and an unauthenticated remote peer can retrigger the condition by sending additional malformed tunnel packets." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/um/drivers/vector_kern.c" ], "versions": [ { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "967c779c9853d2a1cc9cd8e61d300250c348f3d9", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "a7bc015bb798c525e7a82dd14225c6aeb994274b", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "7dc9781e320d664c9bdd50003c9acfddf363d1e1", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "4b9601595e8b6b5d18878cac0aeabc687d241111", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "67d58ab4f2ccf7145f3da07e025735a09c79de1b", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "180ff4c81faf01ec4e06082c9daa7c40518ead89", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "804b681002ead233abf49a3efd681f5468a835f9", "status": "affected", "versionType": "git" }, { "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "af421e9aed3920c7ac88c24daa48606c7112feca", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/um/drivers/vector_kern.c" ], "versions": [ { "version": "4.17", "status": "affected" }, { "version": "0", "lessThan": "4.17", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "4.17", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.6.151" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.12.103" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.18.44" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "7.1.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/967c779c9853d2a1cc9cd8e61d300250c348f3d9" }, { "url": "https://git.kernel.org/stable/c/a7bc015bb798c525e7a82dd14225c6aeb994274b" }, { "url": "https://git.kernel.org/stable/c/7dc9781e320d664c9bdd50003c9acfddf363d1e1" }, { "url": "https://git.kernel.org/stable/c/4b9601595e8b6b5d18878cac0aeabc687d241111" }, { "url": "https://git.kernel.org/stable/c/67d58ab4f2ccf7145f3da07e025735a09c79de1b" }, { "url": "https://git.kernel.org/stable/c/180ff4c81faf01ec4e06082c9daa7c40518ead89" }, { "url": "https://git.kernel.org/stable/c/804b681002ead233abf49a3efd681f5468a835f9" }, { "url": "https://git.kernel.org/stable/c/af421e9aed3920c7ac88c24daa48606c7112feca" } ], "title": "um: vector: fix use-after-free in vector_mmsg_rx()", "x_generator": { "engine": "bippy-1.2.0" } } } }