161 lines
9.5 KiB
JSON
161 lines
9.5 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-2025-21958",
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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": "2024-12-29T08:45:45.791Z",
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"datePublished": "2025-04-01T15:46:57.268Z",
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"dateUpdated": "2026-08-05T11:55:36.868Z"
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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": "2026-08-05T11:55:36.868Z"
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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\nRevert \"openvswitch: switch to per-action label counting in conntrack\"\n\nCurrently, ovs_ct_set_labels() is only called for confirmed conntrack\nentries (ct) within ovs_ct_commit(). However, if the conntrack entry\ndoes not have the labels_ext extension, attempting to allocate it in\novs_ct_get_conn_labels() for a confirmed entry triggers a warning in\nnf_ct_ext_add():\n\n WARN_ON(nf_ct_is_confirmed(ct));\n\nThis happens when the conntrack entry is created externally before OVS\nincrements net->ct.labels_used. The issue has become more likely since\ncommit fcb1aa5163b1 (\"openvswitch: switch to per-action label counting\nin conntrack\"), which changed to use per-action label counting and\nincrement net->ct.labels_used when a flow with ct action is added.\n\nSince there’s no straightforward way to fully resolve this issue at the\nmoment, this reverts the commit to avoid breaking existing use cases."
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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 - Triggering requires installing an OVS datapath flow carrying a ct action with a non-zero label mask via the openvswitch generic-netlink interface, which is a local operation. Although the packet that fires the bug can arrive from the wire on an OVS/OVN host, the necessary local netlink configuration step makes Local the defensible vector.\nAC:L - The attacker fully controls the ordering that creates the bug — create the conntrack entry while net->ct.labels_used is zero, then install the ct-label flow, then re-send a packet of that connection — and equally controls the concurrent traffic that turns the krealloc of a hash-visible ct->ext into a use-after-free. No condition lies outside attacker influence.\nPR:L - All OVS datapath/flow/vport netlink commands use GENL_UNS_ADMIN_PERM, i.e. CAP_NET_ADMIN in the netns owner user namespace, which any unprivileged user obtains with unshare -Urn; nftables in the same namespace supplies the externally created conntrack entry.\nUI:N - The attacker performs every step — namespace setup, flow installation and packet injection — with no action from any other user.\nS:U - The corruption is confined to kernel heap objects belonging to the same kernel security authority; no VM, IOMMU or sandbox boundary is crossed.\nC:H - nf_ct_ext_add() reallocates ct->ext on a confirmed, hash-table-visible conntrack with no RCU grace period, so lock-free readers such as nf_conn_acct_find(), nfct_nat(), nf_ct_ecache_find() and nf_ct_labels_find() dereference freed memory, giving a use-after-free read that can be groomed to disclose arbitrary kernel heap contents.\nI:H - The same window is a use-after-free write — nf_ct_acct_update() performs atomic64_add() into the freed extension block, and nf_ct_ext_add() itself writes offsets and memsets into a buffer another CPU may already have reallocated — yielding heap corruption exploitable for control-flow hijack.\nA:H - The WARN_ON(nf_ct_is_confirmed(ct)) splat is an immediate kernel warning that panics the machine under panic_on_warn, and the underlying use-after-free readily causes oopses and slab corruption crashes."
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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/openvswitch/conntrack.c",
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"net/openvswitch/datapath.h"
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],
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"versions": [
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{
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"version": "fcb1aa5163b1ae4cf2864b688b08927aac51f51e",
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"lessThan": "9e79fdabd52cfce1a021640a81256878a2c516a2",
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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": "fcb1aa5163b1ae4cf2864b688b08927aac51f51e",
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"lessThan": "d91bfc64a4886102746e74d2c6f3a61e9a77fd7d",
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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": "fcb1aa5163b1ae4cf2864b688b08927aac51f51e",
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"lessThan": "1063ae07383c0ddc5bcce170260c143825846b03",
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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/openvswitch/conntrack.c",
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"net/openvswitch/datapath.h"
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],
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"versions": [
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{
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"version": "6.12",
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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": "6.12",
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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": "6.12.20",
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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": "6.13.8",
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"lessThanOrEqual": "6.13.*",
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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": "6.14",
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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": "6.12",
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"versionEndExcluding": "6.12.20"
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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": "6.12",
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"versionEndExcluding": "6.13.8"
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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": "6.12",
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"versionEndExcluding": "6.14"
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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/9e79fdabd52cfce1a021640a81256878a2c516a2"
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},
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{
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"url": "https://git.kernel.org/stable/c/d91bfc64a4886102746e74d2c6f3a61e9a77fd7d"
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},
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{
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"url": "https://git.kernel.org/stable/c/1063ae07383c0ddc5bcce170260c143825846b03"
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}
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],
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"title": "Revert \"openvswitch: switch to per-action label counting in conntrack\"",
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