CVE-2026-80738 (GCVE-0-2026-80738)
Vulnerability from cvelistv5
Published
2026-09-03 08:21
Modified
2026-10-30 12:31
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie
bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer
'sk' with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access
sk->sk_protocol without validating whether 'sk' represents a full socket.
Fix this issue by checking sk->sk_state != TCP_LISTEN before inspecting
sk->sk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie.
Since mini-sockets are never in the TCP_LISTEN state, the condition
short-circuits and prevents dereferencing fullsock-specific fields.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 399040847084a69f345e0a52fd62f04654e0fce3 Version: 399040847084a69f345e0a52fd62f04654e0fce3 Version: 399040847084a69f345e0a52fd62f04654e0fce3 Version: 399040847084a69f345e0a52fd62f04654e0fce3 Version: 399040847084a69f345e0a52fd62f04654e0fce3 Version: 399040847084a69f345e0a52fd62f04654e0fce3 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/core/filter.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
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},
{
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{
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"versionType": "git"
},
{
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"version": "399040847084a69f345e0a52fd62f04654e0fce3",
"versionType": "git"
},
{
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"versionType": "git"
}
]
},
{
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"product": "Linux",
"programFiles": [
"net/core/filter.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.2"
},
{
"lessThan": "5.2",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.191",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.57",
"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": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.191",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.160",
"versionStartIncluding": "5.2",
"vulnerable": true
},
{
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{
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{
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{
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"versionStartIncluding": "5.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie\n\nbpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer\n\u0027sk\u0027 with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access\nsk-\u003esk_protocol without validating whether \u0027sk\u0027 represents a full socket.\n\nFix this issue by checking sk-\u003esk_state != TCP_LISTEN before inspecting\nsk-\u003esk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie.\nSince mini-sockets are never in the TCP_LISTEN state, the condition\nshort-circuits and prevents dereferencing fullsock-specific fields."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.3,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The flaw is in bpf_tcp_gen_syncookie/bpf_tcp_check_syncookie BPF helpers invoked only from locally loaded and attached TC clsact or XDP programs via bpf(); per kernel CNA guidance BPF/tc paths are Local even when later triggered by ingress packets.\nAC:L - An attacker who loads the BPF program fully controls passing bpf_skc_lookup_tcp() results (request_sock/TCP_NEW_SYN_RECV or timewait sockets) into the syncookie helpers and can reliably trigger the bad sk_protocol read with crafted SYN/ACK traffic; no uncontrollable races or rare layout are required.\nPR:L - Exploitation requires bpf(BPF_PROG_LOAD) (CAP_BPF, obtainable in user namespaces) plus attaching TC/XDP hooks (CAP_NET_ADMIN via unshare -Urn); no init-namespace root is needed, matching CNA guidance for namespace-reachable net/BPF capabilities.\nUI:N - No victim mount, login, or cooperative action is required; once the attacker loads and attaches their BPF program, sending network packets from their own processes deterministically reaches the vulnerable helper on each matching lookup.\nS:U - Impact is confined to kernel heap disclosure/type confusion within the host kernel security domain; it does not cross VM, container runtime, IOMMU, or other security-authority boundaries.\nC:H - Casting a mini-socket to struct sock and reading sk_protocol performs a fixed-offset out-of-bounds read (~300+ bytes past request_sock/inet_timewait_sock) into adjacent slab memory, leaking kernel heap contents including pointers usable for further local exploitation.\nI:H - This is type confusion between ARG_PTR_TO_BTF_ID_SOCK_COMMON mini-sockets and full struct sock fields; per CNA guidance type confusion is rated High integrity impact even though the immediate bug is a read, because mis-typed socket pointers corrupt the kernel\u0027s object model.\nA:L - The primary impact is information disclosure; while the out-of-bounds u16 read usually stays within the slab page, reads near allocation boundaries or under KASAN can fault and oops the kernel, giving at least Low availability impact when uncertain."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:31:02.208Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b75f1c071f31be7f4b950721e04240c250091ad4"
},
{
"url": "https://git.kernel.org/stable/c/5702e4c259809c760912c477c4ae34e9217bb4d9"
},
{
"url": "https://git.kernel.org/stable/c/b5525e853a2a08a9559adb84b0616025958dc542"
},
{
"url": "https://git.kernel.org/stable/c/22c2169770ad3b3595690e51caac875178cf496d"
},
{
"url": "https://git.kernel.org/stable/c/23f682083aa3fbc0c49667818efd6979a8bc5ac2"
},
{
"url": "https://git.kernel.org/stable/c/31a420a822ff92e2090bd5d65efe8e34e2d6d9b8"
}
],
"title": "bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-80738",
"datePublished": "2026-09-03T08:21:53.143Z",
"dateReserved": "2026-08-26T14:34:25.789Z",
"dateUpdated": "2026-10-30T12:31:02.208Z",
"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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