CVE-2026-74582 (GCVE-0-2026-74582)
Vulnerability from cvelistv5
Published
2026-08-21 16:31
Modified
2026-08-27 12:39
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
packet: use consistent hard_header_len in non-ring send paths
packet_snd() reads dev->hard_header_len multiple times while allocating
and constructing an skb. Device reconfiguration can change this value
concurrently, for example through bonding device type changes.
For SOCK_RAW, packet_snd() can save a larger value in reserve and later
allocate headroom using a smaller value. Moving skb->data back by reserve
then places it before skb->head, and the following copy from userspace can
attempt an out-of-bounds write.
packet_sendmsg_spkt() has the same issue because it calculates its
reservation and header offset from separate reads before dropping the RCU
read lock to allocate the skb.
Add LL_RESERVED_SPACE_EX() for callers that already saved a header length.
Read hard_header_len once in packet_snd() and use it for allocation and
construction. In packet_sendmsg_spkt(), preserve the allocation-time value
through the device lookup retry.
The separate SOCK_DGRAM consistency problem between hard_header_len and
header_ops->create is not addressed here.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: b84bbaf7a6c8cca24f8acf25a2c8e46913a947ba Version: d9fb8cc230b2a4757e9fe4f81468f81212d4deaa Version: 6190cce26e40bf71c4d375b21eea74bb07b6a0f3 Version: 01a658c1b9d4b5393c38d5a92d9112ab1425382a Version: 8809ae6747e760e6f1d2453ceb08c9bcc4939766 Version: 4.4.133 ≤ Version: 4.9.103 ≤ Version: 4.14.44 ≤ Version: 4.16.12 ≤ |
||
{
"containers": {
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},
{
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"vendor": "Linux",
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{
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{
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"versionType": "original_commit_for_fix"
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]
}
],
"cpeApplicability": [
{
"nodes": [
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{
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"negate": false,
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\npacket: use consistent hard_header_len in non-ring send paths\n\npacket_snd() reads dev-\u003ehard_header_len multiple times while allocating\nand constructing an skb. Device reconfiguration can change this value\nconcurrently, for example through bonding device type changes.\n\nFor SOCK_RAW, packet_snd() can save a larger value in reserve and later\nallocate headroom using a smaller value. Moving skb-\u003edata back by reserve\nthen places it before skb-\u003ehead, and the following copy from userspace can\nattempt an out-of-bounds write.\n\npacket_sendmsg_spkt() has the same issue because it calculates its\nreservation and header offset from separate reads before dropping the RCU\nread lock to allocate the skb.\n\nAdd LL_RESERVED_SPACE_EX() for callers that already saved a header length.\nRead hard_header_len once in packet_snd() and use it for allocation and\nconstruction. In packet_sendmsg_spkt(), preserve the allocation-time value\nthrough the device lookup retry.\n\nThe separate SOCK_DGRAM consistency problem between hard_header_len and\nheader_ops-\u003ecreate is not addressed here."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The flaw is in packet_snd() and packet_sendmsg_spkt() on the local AF_PACKET sendmsg() transmit path; it is not triggered by processing remotely received network traffic or pre-authentication network services.\nAC:L - An attacker in a user+network namespace can open an AF_PACKET SOCK_RAW socket and concurrently reconfigure the bound netdev (bonding/VLAN/macvlan/team) to change hard_header_len, controlling both sides of the race without external timing.\nPR:L - Exploitation requires CAP_NET_RAW to create AF_PACKET sockets and CAP_NET_ADMIN to change netdev hard_header_len; both are obtainable by an unprivileged user inside a user namespace without init-namespace root.\nUI:N - No victim interaction is required; the attacker triggers the bug using their own packet socket sendmsg calls and concurrent netdev reconfiguration threads.\nS:U - Impact is kernel heap corruption and local privilege escalation within the same kernel security domain; it does not constitute a VM escape, sandbox breakout, or IOMMU boundary bypass.\nC:H - Racing hard_header_len can place skb-\u003edata before skb-\u003ehead, and skb_copy_datagram_from_iter/memcpy_from_msg then writes attacker-controlled data outside the skb buffer, corrupting adjacent slab objects and enabling kernel memory disclosure.\nI:H - Inconsistent hard_header_len between skb allocation and header adjustment causes out-of-bounds kernel heap writes of attacker-controlled packet data, yielding corruption primitives suitable for control-flow hijacking and local privilege escalation.\nA:H - Out-of-bounds skb buffer writes corrupt kmalloc metadata and can trigger kernel oops/panic, causing reliable denial of service even when full exploitation is not completed."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T12:39:47.499Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/bcd4df60ac9481b1ceffdfe5ec38fe51dcaae812"
},
{
"url": "https://git.kernel.org/stable/c/78a47127e33c340bc6d38dcc4552a094b4f5cc77"
},
{
"url": "https://git.kernel.org/stable/c/142e287b3a25cfe909215177c23243e7fc5ae2b1"
},
{
"url": "https://git.kernel.org/stable/c/91f041451f967cd87ed722a8f43c0b767a64f1a0"
},
{
"url": "https://git.kernel.org/stable/c/9052756290962ffb9a661bcf319e92dedaaedfed"
},
{
"url": "https://git.kernel.org/stable/c/5bb10753d428aadfc356a2bfe9acea09c82a62ec"
},
{
"url": "https://git.kernel.org/stable/c/b06b6fce6d7deaf7238e09b48ce3b1125ff41acd"
},
{
"url": "https://git.kernel.org/stable/c/03390aa32e669cc4ecd7d34108e2e1afc13d689d"
}
],
"title": "packet: use consistent hard_header_len in non-ring send paths",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74582",
"datePublished": "2026-08-21T16:31:55.283Z",
"dateReserved": "2026-08-15T05:44:03.918Z",
"dateUpdated": "2026-08-27T12:39:47.499Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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