{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63926", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.021Z", "datePublished": "2026-07-19T14:55:27.154Z", "dateUpdated": "2026-08-05T12:37:21.277Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:21.277Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: sockmap: fix tail fragment offset in bpf_msg_push_data\n\nWhen bpf_msg_push_data() inserts data in the middle of a scatterlist\nentry, it splits the original entry into a left fragment and a right\nfragment.\n\nThe right fragment offset is page-local, but the code advances it with\n`start`, which is the message-global insertion point. For inserts into a\nnon-first SG entry, this over-advances the offset and leaves the split\nlayout inconsistent.\n\nAdvance the right fragment offset by the fragment-local delta,\n`start - offset`, which matches the length removed from the front of the\noriginal entry." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached through the BPF sk_msg/sockmap send path (sendmsg → tcp_bpf_send_verdict → sk_psock_msg_verdict → bpf_msg_push_data), which requires local syscalls and BPF setup; per kernel CNA guidance, BPF/sockmap issues are scored as Local rather than Network.\nAC:L - An attacker who can load a sk_msg BPF program fully controls the insertion offset and can reliably build multi-fragment scatterlist messages (e.g., via large sendmsg/sendfile) to hit the non-first-entry split path; a public PoC demonstrates deterministic triggering without races or external victim state.\nPR:N - While direct exploitation requires CAP_NET_ADMIN+CAP_BPF to load sockmap/sk_msg programs (obtainable as PR:L via user namespaces), the highest-impact reasonable scenario is an unauthenticated remote client triggering a pre-deployed internet-facing kTLS/sockmap proxy whose sk_msg BPF calls bpf_msg_push_data during outbound processing, requiring no privileges on the victim host.\nUI:N - Exploitation requires no victim user interaction beyond normal network I/O to a service that already runs sockmap/sk_msg BPF; the attacker does not need the victim to mount filesystems, open files, or take other deliberate actions.\nS:U - Impact is kernel heap memory corruption within the same kernel security authority (privilege escalation, memory disclosure, or crash), not a cross-boundary escape such as VM guest-to-host or IOMMU bypass.\nC:H - The incorrect rsge.offset over-advances the page-local offset for non-first scatterlist fragments, causing out-of-bounds reads when subsequent helpers (e.g., bpf_msg_pull_data via sg_virt/memcpy) or the TCP send path consume the corrupted entry; the public PoC shows a 32,752-byte OOB read/UAF.\nI:H - Scatterlist metadata corruption produces inconsistent length/offset pairs that can drive out-of-bounds kernel memory access and is a standard heap corruption primitive potentially weaponizable for arbitrary write or control-flow hijack, not merely a bounded data error.\nA:H - Corrupted scatterlist state can cause kernel oops/panic from out-of-bounds page access (as shown in the PoC KASAN trace) or destabilize subsequent sk_msg/TCP/kTLS transmit processing, resulting in denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/filter.c" ], "versions": [ { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "f14609d8146707452e0822f3c8154674ce677251", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "d81b323af2dcee47573907ccb89c0df9b45cb2e2", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "aeb95146848d12206e1b2cfacd4f40e21ce81d94", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "96b72672ce849a1402730238e64d9b20bf06a96d", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "3075c21d2d76c0067f4a382765b43d6cc10470f1", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "5e19028667963fb371ebb00cecc2a473ef92056b", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "63f64a510c7917658ddf4d073ece73914ee25346", "status": "affected", "versionType": "git" }, { "version": "6fff607e2f14bd7c63c06c464a6f93b8efbabe28", "lessThan": "f72eed9b84fb771019a955908132410a9ba9ea3f", "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/core/filter.c" ], "versions": [ { "version": "4.20", "status": "affected" }, { "version": "0", "lessThan": "4.20", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "4.20", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f14609d8146707452e0822f3c8154674ce677251" }, { "url": "https://git.kernel.org/stable/c/d81b323af2dcee47573907ccb89c0df9b45cb2e2" }, { "url": "https://git.kernel.org/stable/c/aeb95146848d12206e1b2cfacd4f40e21ce81d94" }, { "url": "https://git.kernel.org/stable/c/96b72672ce849a1402730238e64d9b20bf06a96d" }, { "url": "https://git.kernel.org/stable/c/3075c21d2d76c0067f4a382765b43d6cc10470f1" }, { "url": "https://git.kernel.org/stable/c/5e19028667963fb371ebb00cecc2a473ef92056b" }, { "url": "https://git.kernel.org/stable/c/63f64a510c7917658ddf4d073ece73914ee25346" }, { "url": "https://git.kernel.org/stable/c/f72eed9b84fb771019a955908132410a9ba9ea3f" } ], "title": "bpf: sockmap: fix tail fragment offset in bpf_msg_push_data", "x_generator": { "engine": "bippy-1.2.0" } } } }