159 lines
9.0 KiB
JSON
159 lines
9.0 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-2026-43254",
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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": "2026-05-01T14:12:55.996Z",
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"datePublished": "2026-05-06T11:28:43.871Z",
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"dateUpdated": "2026-08-05T12:26:54.790Z"
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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": "2026-08-05T12:26:54.790Z"
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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\novpn: tcp - fix packet extraction from stream\n\nWhen processing TCP stream data in ovpn_tcp_recv, we receive large\ncloned skbs from __strp_rcv that may contain multiple coalesced packets.\nThe current implementation has two bugs:\n\n1. Header offset overflow: Using pskb_pull with large offsets on\n coalesced skbs causes skb->data - skb->head to exceed the u16 storage\n of skb->network_header. This causes skb_reset_network_header to fail\n on the inner decapsulated packet, resulting in packet drops.\n\n2. Unaligned protocol headers: Extracting packets from arbitrary\n positions within the coalesced TCP stream provides no alignment\n guarantees for the packet data causing performance penalties on\n architectures without efficient unaligned access. Additionally,\n openvpn's 2-byte length prefix on TCP packets causes the subsequent\n 4-byte opcode and packet ID fields to be inherently misaligned.\n\nFix both issues by allocating a new skb for each openvpn packet and\nusing skb_copy_bits to extract only the packet content into the new\nbuffer, skipping the 2-byte length prefix. Also, check the length before\ninvoking the function that performs the allocation to avoid creating an\ninvalid skb.\n\nIf the packet has to be forwarded to userspace the 2-byte prefix can be\npushed to the head safely, without misalignment.\n\nAs a side effect, this approach also avoids the expensive linearization\nthat pskb_pull triggers on cloned skbs with page fragments. In testing,\nthis resulted in TCP throughput improvements of up to 74%."
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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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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"baseScore": 7.5,
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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:N - The vulnerable parser is reached by TCP stream data received from a remote OpenVPN peer over the network.\nAC:L - The attacker controls the TCP byte stream and OpenVPN length-prefixed records; no race or condition outside attacker control is required.\nPR:N - Local CAP_NET_ADMIN is needed only to configure the ovpn device and attach the socket, not to send the triggering network data once the service is exposed.\nUI:N - No victim user action is needed beyond the already-running OpenVPN TCP deployment.\nS:U - The impact remains within the kernel/OpenVPN networking security authority and does not cross a VM, sandbox, or hardware isolation boundary.\nC:N - The traced path leads to packet extraction/header-offset failure and drops, with no demonstrated kernel memory disclosure primitive.\nI:N - The bug corrupts skb parsing state/alignment but does not provide a demonstrated ability to modify kernel memory or protected data.\nA:H - A remote sender can repeatedly trigger packet drops in the ovpn TCP data path, and on strict-alignment systems the unaligned kernel accesses can severely disrupt or crash the data channel."
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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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"drivers/net/ovpn/tcp.c"
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],
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"versions": [
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{
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"version": "11851cbd60ea1e5abbd97619d69845ead99303d6",
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"lessThan": "0315bec883c67fa1413c61e504a28dc5bd02eb37",
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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": "11851cbd60ea1e5abbd97619d69845ead99303d6",
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"lessThan": "7dba6cd7fb168d7615194a631c9c100c1c224131",
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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": "11851cbd60ea1e5abbd97619d69845ead99303d6",
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"lessThan": "d4f687fbbce45b5e88438e89b5e26c0c15847992",
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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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"drivers/net/ovpn/tcp.c"
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],
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"versions": [
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{
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"version": "6.16",
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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": "6.16",
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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": "6.18.16",
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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": "6.19.6",
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"lessThanOrEqual": "6.19.*",
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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": "7.0",
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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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"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": "6.16",
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"versionEndExcluding": "6.18.16"
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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": "6.16",
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"versionEndExcluding": "6.19.6"
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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": "6.16",
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"versionEndExcluding": "7.0"
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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/0315bec883c67fa1413c61e504a28dc5bd02eb37"
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},
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{
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"url": "https://git.kernel.org/stable/c/7dba6cd7fb168d7615194a631c9c100c1c224131"
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},
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{
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"url": "https://git.kernel.org/stable/c/d4f687fbbce45b5e88438e89b5e26c0c15847992"
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}
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],
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"title": "ovpn: tcp - fix packet extraction from stream",
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"x_generator": {
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