CVE-2026-72057 (GCVE-0-2026-72057)
Vulnerability from cvelistv5
Published
2026-08-15 05:52
Modified
2026-08-23 12:46
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: act_ct: preserve tc_skb_cb across defragmentation
tcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving
and restoring skb->cb. The defrag helper clears IPCB/IP6CB, which aliases
the tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through
act_ct therefore loses qdisc metadata such as pkt_segs and can trigger
WARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.
Save and restore the full tc_skb_cb around nf_ct_handle_fragments(),
matching the pattern used by ovs_ct_handle_fragments().
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 0d76daf2013ce1da20eab5e26bd81d983e1c18fb Version: ec624fe740b416fb68d536b37fb8eef46f90b5c2 Version: ec624fe740b416fb68d536b37fb8eef46f90b5c2 Version: ec624fe740b416fb68d536b37fb8eef46f90b5c2 Version: ec624fe740b416fb68d536b37fb8eef46f90b5c2 Version: ec624fe740b416fb68d536b37fb8eef46f90b5c2 Version: ec624fe740b416fb68d536b37fb8eef46f90b5c2 Version: 5.15.13 ≤ |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/sched/act_ct.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "0d76daf2013ce1da20eab5e26bd81d983e1c18fb",
"versionType": "git"
},
{
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"status": "affected",
"version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
"versionType": "git"
},
{
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"status": "affected",
"version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
"versionType": "git"
},
{
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"status": "affected",
"version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
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{
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"status": "affected",
"version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
"versionType": "git"
},
{
"lessThan": "9092e15defbe6c7bc241c306093ca9d358a578e7",
"status": "affected",
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"versionType": "git"
},
{
"lessThan": "5.15.217",
"status": "affected",
"version": "5.15.13",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/sched/act_ct.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.16"
},
{
"lessThan": "5.16",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.217",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.184",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"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": "5.15.217",
"versionStartIncluding": "5.15.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.184",
"versionStartIncluding": "5.16",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.145",
"versionStartIncluding": "5.16",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.97",
"versionStartIncluding": "5.16",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.40",
"versionStartIncluding": "5.16",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
"versionStartIncluding": "5.16",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "5.16",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: preserve tc_skb_cb across defragmentation\n\ntcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving\nand restoring skb-\u003ecb. The defrag helper clears IPCB/IP6CB, which aliases\nthe tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through\nact_ct therefore loses qdisc metadata such as pkt_segs and can trigger\nWARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.\n\nSave and restore the full tc_skb_cb around nf_ct_handle_fragments(),\nmatching the pattern used by ovs_ct_handle_fragments()."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.2,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The bug fires in tcf_ct_act() on the packet datapath (sch_handle_ingress/egress \u2192 tc_run \u2192 tcf_classify) when IP fragments arrive; on OVN/Kubernetes/SDN gateways and mlx5 offload nodes with act_ct already installed, a remote peer triggers it by sending fragmented traffic with no local access.\nAC:L - The attacker fully controls fragment boundaries and ordering; nf_ct_handle_fragments() memset of IPCB/IP6CB that aliases tc_skb_cb runs deterministically on each matching fragment through the configured ct action without races or memory-layout dependencies.\nPR:N - Installing act_ct requires CAP_NET_ADMIN, but triggering the bug on an already-configured internet-facing or tenant-facing gateway needs no target credentials; a remote attacker only sends crafted IP fragments, matching CNA precedent for packet-driven act_ct issues (e.g., CVE-2023-52610).\nUI:N - Exploitation requires only attacker-generated fragmented packets reaching a host with act_ct on clsact/ingress; no victim login, mount, or other interactive action is needed.\nS:U - WARN/panic and corrupted qdisc/tc metadata occur entirely within the host kernel security domain; this is not a VM escape, sandbox breakout, or IOMMU boundary bypass.\nC:N - memset(IPCB/IP6CB) zeroes tc_skb_cb/qdisc_skb_cb fields in place without out-of-bounds read or use-after-free; no kernel memory contents are disclosed to the attacker, only skb control-block metadata is clobbered.\nI:L - Clearing pkt_segs, pkt_len, post_ct, and zone corrupts tc/qdisc state consumed by bstats_update, sch_cake/sch_qfq, and cls_flower zone matching, enabling attacker-driven mis-accounting and mis-handling of packets on the affected path.\nA:H - Zeroed pkt_segs makes qdisc_pkt_segs() hit DEBUG_NET_WARN_ON_ONCE when it disagrees with GSO segment count; with panic_on_warn enabled this kernel-panics the host, and the condition is repeatable with sustained fragmented traffic."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-23T12:46:36.427Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/fb080b6f54835d5d4d11ce3122800e6f0f6689e6"
},
{
"url": "https://git.kernel.org/stable/c/67d6b00a54446c008f52cf70fc0c2ad0c712f85d"
},
{
"url": "https://git.kernel.org/stable/c/2400c4b05d58834b994500a9eec90a37db44187c"
},
{
"url": "https://git.kernel.org/stable/c/5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac"
},
{
"url": "https://git.kernel.org/stable/c/b3d835407846134b0d54637c0281b39bebef831d"
},
{
"url": "https://git.kernel.org/stable/c/f7f45ceb855d9ba1cba594fb3f383255f7013fad"
},
{
"url": "https://git.kernel.org/stable/c/9092e15defbe6c7bc241c306093ca9d358a578e7"
}
],
"title": "net/sched: act_ct: preserve tc_skb_cb across defragmentation",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-72057",
"datePublished": "2026-08-15T05:52:12.873Z",
"dateReserved": "2026-08-09T03:40:39.903Z",
"dateUpdated": "2026-08-23T12:46:36.427Z",
"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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