CVE-2026-98955 (GCVE-0-2026-98955)
Vulnerability from cvelistv5
Published
2026-10-23 12:19
Modified
2026-10-30 12:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
flow_dissector: avoid u16 truncation of skb->len when computing thoff
__skb_flow_dissect() computes key_control->thoff using:
key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen);
min_t(u16, ...) casts both arguments to u16 before comparing them.
Whenever skb->len (or hlen) modulo 65536 is smaller than nhoff, the
truncated length wins and thoff is set to a bogus small value, even
when the dissection succeeded. For example, an IPv4/TCP frame with
skb->len == 65540 and nhoff == 34 gets thoff == 4, so callers such as
skb_probe_transport_header() point the transport header inside the
Ethernet header.
Such skbs are not exotic:
- At the time of commit d0c081b49137 ("flow_dissector: properly cap
thoff field"), AF_PACKET with PACKET_VNET_HDR could already build GSO
skbs larger than 64KB (MTU checks are skipped for GSO, and
alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0
pages on top of the linear part).
- BIG TCP now makes skbs larger than 64KB common.
- The following patch makes tun_get_user() dissect IFF_TAP frames
before eth_type_trans() pulls the Ethernet header, so a GSO frame
carrying a 65522..65535 byte L3 packet will be dissected with
skb->len in [65536, 65549].
Compare as u32 instead. If the resulting offset cannot be represented
in the u16 key_control->thoff, cap it to U16_MAX and report the
dissection as failed rather than silently returning a wrong transport
offset. thoff is still set on failure, as some callers (such as
eth_get_headlen()) use it regardless of the return value.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d0c081b49137cd3200f2023c0875723be66e7ce5 Version: d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc Version: eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1 Version: 80f327285cab6ab8e10c3ea03278add5dd99fb02 Version: 4.4.114 ≤ Version: 4.9.79 ≤ Version: 4.14.16 ≤ |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/core/flow_dissector.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3f6000fdf8a57b9786669869af8a3e050b541bf3",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "2c2f82b696c5e877f60ea77b7784e906a5e63014",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "d44e66f5dd99319a32e378b610af7fcf78da985a",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "d9e08836d06c84abb18470c94b12b131eaccdc7d",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "50d0cd575cab763f833d6ac6eb6550b23a0b3dae",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "9993e6a0ac1b5b3101ffba702cacb9f42b9909d8",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "52efce4755a4b8b82039caa773645ffc80b25362",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"lessThan": "99bda1ecbd56905f8bd934b9cdccd3bd251192b1",
"status": "affected",
"version": "d0c081b49137cd3200f2023c0875723be66e7ce5",
"versionType": "git"
},
{
"status": "affected",
"version": "d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc",
"versionType": "git"
},
{
"status": "affected",
"version": "eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1",
"versionType": "git"
},
{
"status": "affected",
"version": "80f327285cab6ab8e10c3ea03278add5dd99fb02",
"versionType": "git"
},
{
"lessThan": "4.5",
"status": "affected",
"version": "4.4.114",
"versionType": "semver"
},
{
"lessThan": "4.10",
"status": "affected",
"version": "4.9.79",
"versionType": "semver"
},
{
"lessThan": "4.15",
"status": "affected",
"version": "4.14.16",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/core/flow_dissector.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.15"
},
{
"lessThan": "4.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.273",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.224",
"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": "6.12.113",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.11",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.273",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.224",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.191",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.160",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.113",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.57",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.11",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "4.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4.114",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.9.79",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.14.16",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nflow_dissector: avoid u16 truncation of skb-\u003elen when computing thoff\n\n__skb_flow_dissect() computes key_control-\u003ethoff using:\n\n key_control-\u003ethoff = min_t(u16, nhoff, skb ? skb-\u003elen : hlen);\n\nmin_t(u16, ...) casts both arguments to u16 before comparing them.\nWhenever skb-\u003elen (or hlen) modulo 65536 is smaller than nhoff, the\ntruncated length wins and thoff is set to a bogus small value, even\nwhen the dissection succeeded. For example, an IPv4/TCP frame with\nskb-\u003elen == 65540 and nhoff == 34 gets thoff == 4, so callers such as\nskb_probe_transport_header() point the transport header inside the\nEthernet header.\n\nSuch skbs are not exotic:\n- At the time of commit d0c081b49137 (\"flow_dissector: properly cap\n thoff field\"), AF_PACKET with PACKET_VNET_HDR could already build GSO\n skbs larger than 64KB (MTU checks are skipped for GSO, and\n alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0\n pages on top of the linear part).\n- BIG TCP now makes skbs larger than 64KB common.\n- The following patch makes tun_get_user() dissect IFF_TAP frames\n before eth_type_trans() pulls the Ethernet header, so a GSO frame\n carrying a 65522..65535 byte L3 packet will be dissected with\n skb-\u003elen in [65536, 65549].\n\nCompare as u32 instead. If the resulting offset cannot be represented\nin the u16 key_control-\u003ethoff, cap it to U16_MAX and report the\ndissection as failed rather than silently returning a wrong transport\noffset. thoff is still set on failure, as some callers (such as\neth_get_headlen()) use it regardless of the return value."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:40:30.324Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/3f6000fdf8a57b9786669869af8a3e050b541bf3"
},
{
"url": "https://git.kernel.org/stable/c/2c2f82b696c5e877f60ea77b7784e906a5e63014"
},
{
"url": "https://git.kernel.org/stable/c/d44e66f5dd99319a32e378b610af7fcf78da985a"
},
{
"url": "https://git.kernel.org/stable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d"
},
{
"url": "https://git.kernel.org/stable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae"
},
{
"url": "https://git.kernel.org/stable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8"
},
{
"url": "https://git.kernel.org/stable/c/52efce4755a4b8b82039caa773645ffc80b25362"
},
{
"url": "https://git.kernel.org/stable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1"
}
],
"title": "flow_dissector: avoid u16 truncation of skb-\u003elen when computing thoff",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-98955",
"datePublished": "2026-10-23T12:19:15.287Z",
"dateReserved": "2026-09-25T10:25:14.382Z",
"dateUpdated": "2026-10-30T12:40:30.324Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
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.
Loading…
Loading…