224 lines
13 KiB
JSON
224 lines
13 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-98368",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-25T10:25:14.344Z",
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"datePublished": "2026-10-06T08:46:53.292Z",
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"dateUpdated": "2026-10-19T09:18:20.253Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-19T09:18:20.253Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp->inplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb. This breaks the managed-frag invariant two ways:\n\n - esp_ssg_unref() walks the source scatterlist and drops a page\n reference for every frag, including the ubuf-owned payload frags,\n pushing their refcount below the GUP pin bias while the pages are\n still pinned, i.e. a use-after-free of the zerocopy pages;\n\n - esp_output_tail() installs its destination page as frag 0 with\n get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n skb_release_data() takes the skip_unref branch and never drops that\n reference, leaking the x->xfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - Managed frags are set only by io_uring's io_sg_from_iter() for IORING_OP_SEND_ZC/SENDMSG_ZC with IORING_RECVSEND_FIXED_BUF, so a local process must submit the zerocopy send that esp_output_head()/esp6_output_head() then mutates; a remote peer cannot produce a SKBFL_MANAGED_FRAG_REFS skb.\nAC:L - The attacker picks every input: an uncloned UDP skb whose data_len+tailen fits in a page and lacks tailroom reliably takes the esp->inplace=false branch, then esp_ssg_unref() drops refs on the ubuf-owned frags. No race or outside state is needed.\nPR:L - io_uring zerocopy send needs no privilege. The ESP SA/policy can be added inside an unprivileged user+net namespace because xfrm_user_rcv_msg only checks netlink_net_capable(CAP_NET_ADMIN); on a host with IPsec already set up, any local user's traffic hits it.\nUI:N - The attacker does everything with their own io_uring ring, registered buffer, socket and (namespaced) xfrm state; no other user has to act.\nS:U - The page refcount underflow and the freed page stay inside the kernel's own authority, so this is a normal local privilege escalation with no VM or sandbox boundary crossed.\nC:H - esp_ssg_unref() pushes the pinned registered-buffer pages' refcount below the GUP pin bias, so the page is freed while io_uring still has it mapped; once reallocated (e.g. as page tables or slab) the attacker can read kernel memory through the stale buffer.\nI:H - Writing through the still-registered fixed buffer into the freed and reallocated page is a page-level use-after-free write primitive (Dirty-Pagetable style), enough for arbitrary kernel memory corruption and privilege escalation.\nA:H - The page UAF leads to bad-page/refcount oopses, and the missing put_page on the x->xfrag page installed by esp_output_tail() leaks memory at packet rate; both can take the system down."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/ipv4/esp4.c",
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"net/ipv6/esp6.c"
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],
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"versions": [
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{
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"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
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"lessThan": "2359264f377cdbdef2d95868cc8fb572949e48d3",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
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"lessThan": "69a768c12398cada8528080332c822623fa7064d",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
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"lessThan": "6508304ac2c8cdafca2f4ab915df8c707893e134",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
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"lessThan": "6cab554f2c0f28773f712ed3a5479103f42ce844",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
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"lessThan": "0d0845ee61c5df47cc68bc446501f48f71e8dcc6",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
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"lessThan": "f89416eb3db151170a6f3c6dfc5239d26cdce4d2",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/ipv4/esp4.c",
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"net/ipv6/esp6.c"
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],
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"versions": [
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{
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"version": "6.0",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.0",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.189",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.158",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.112",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.54",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.8",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.0",
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"versionEndExcluding": "6.1.189"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.0",
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"versionEndExcluding": "6.6.158"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.0",
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"versionEndExcluding": "6.12.112"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.0",
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"versionEndExcluding": "6.18.54"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.0",
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"versionEndExcluding": "7.2.8"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.0",
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"versionEndExcluding": "7.3"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"
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},
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{
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"url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"
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},
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{
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"url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"
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},
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{
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"url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"
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},
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{
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"url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"
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},
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{
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"url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"
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}
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],
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"title": "esp: downgrade zerocopy managed frags before mutating skb frags",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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}
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}
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} |