CVE-2026-74668 (GCVE-0-2026-74668)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-27 12:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
packet: use consistent hard_header_len in TX_RING send path
tpacket_snd() reads dev->hard_header_len independently for skb
allocation and header construction in tpacket_fill_skb(). Concurrent
netdevice reconfiguration can therefore make the reserved headroom
smaller than the amount later pushed, or make copylen - hard_header_len
negative.
Snapshot hard_header_len once before processing ring frames and use it
for the frame limit, headroom allocation, copy length, and skb
construction. Pass the snapshot to tpacket_fill_skb().
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: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 Version: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/packet/af_packet.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"version": "69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1",
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{
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"programFiles": [
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],
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"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.31"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.267",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.218",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.185",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
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"versionStartIncluding": "2.6.31",
"vulnerable": true
},
{
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{
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{
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{
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"versionStartIncluding": "2.6.31",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\npacket: use consistent hard_header_len in TX_RING send path\n\ntpacket_snd() reads dev-\u003ehard_header_len independently for skb\nallocation and header construction in tpacket_fill_skb(). Concurrent\nnetdevice reconfiguration can therefore make the reserved headroom\nsmaller than the amount later pushed, or make copylen - hard_header_len\nnegative.\n\nSnapshot hard_header_len once before processing ring frames and use it\nfor the frame limit, headroom allocation, copy length, and skb\nconstruction. Pass the snapshot to tpacket_fill_skb().\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 reached only via local syscalls on an AF_PACKET socket with PACKET_TX_RING configured (sendmsg on mmap ring frames); it is not triggered by processing remotely received network traffic.\nAC:L - An attacker can open the TX_RING socket and concurrently reconfigure the bound netdev (e.g., VLAN/bonding/macvlan changes) in a user+network namespace, controlling both sides of the hard_header_len race without depending on 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, TX_RING, and 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 make skb_push exceed reserved headroom or skb_put use a negative length (huge unsigned), and subsequent skb_store_bits writes before skb-\u003ehead or far past skb-\u003etail, corrupting adjacent slab objects and enabling kernel memory disclosure.\nI:H - Inconsistent hard_header_len between skb allocation and tpacket_fill_skb causes out-of-bounds linear expansion and data writes in the skb buffer, yielding heap corruption primitives suitable for control-flow hijacking and local privilege escalation.\nA:H - Corrupted skb_push/put operations invoke skb_under_panic or skb_over_panic (BUG), causing kernel oops/panic and reliable denial of service even when exploitation is not completed."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T12:40:01.903Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/9c7e8ff48c377bef18c3d178748aea0575b69ede"
},
{
"url": "https://git.kernel.org/stable/c/2a73b2c37ee3060a880b53cd24783d93fc7be5f8"
},
{
"url": "https://git.kernel.org/stable/c/e79f59a8527a49078cfaf8fe8fb5fcefc20c76d2"
},
{
"url": "https://git.kernel.org/stable/c/d85d2fd54e901637c81d847811e03c662aee13cd"
},
{
"url": "https://git.kernel.org/stable/c/016763e829cac37b3234eace86fd0a4c560de4a7"
},
{
"url": "https://git.kernel.org/stable/c/27e068d1b35dbec10a3cf268887c94407be4badc"
},
{
"url": "https://git.kernel.org/stable/c/d48ea5c9c4c34dc0df621f0e39ed3a16b644621a"
},
{
"url": "https://git.kernel.org/stable/c/21b5953e7494c16a42e6cd8cf110e18d13ae4a6b"
}
],
"title": "packet: use consistent hard_header_len in TX_RING send path",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74668",
"datePublished": "2026-08-22T15:32:39.583Z",
"dateReserved": "2026-08-15T05:44:03.924Z",
"dateUpdated": "2026-08-27T12:40:01.903Z",
"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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