CVE-2026-72338 (GCVE-0-2026-72338)
Vulnerability from cvelistv5
Published
2026-08-15 05:55
Modified
2026-08-17 05:42
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload
There is a TOCTOU race condition in flower lockless approach between sizing
a flow_rule buffer and filling it.
zdi-disclosures@trendmicro.com reports:
The cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED
(fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the
independent locking domains make the race reachable in practice. KASAN
confirms:
BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930
Write of size 4 at addr ffff888001f27520 by task poc-toctou/312
The buggy address is located 0 bytes to the right of
allocated 288-byte region [ffff888001f27400, ffff888001f27520)
(cache kmalloc-512)
Note: The result is a heap OOB write attacker-controlled content into the
adjacent slab object (requires CAP_NET_ADMIN).
The fix introduces reading tcfp_nkeys under act->tcfa_lock in all places
using a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys().
Additionally we close the remaining TOCTOU window between the sizing read and
the fill reads by more careful accounting.
Rather than silently truncating the key count, which leads to incorrect
action semantics offloaded to hardware and secondary OOB writes if
the remaining capacity is zero or consumed by prior actions, we enforce
remaining capacity checks and return -ENOSPC if the required space exceeds
the remaining capacity.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"include/net/tc_act/tc_pedit.h",
"net/sched/act_api.c",
"net/sched/act_pedit.c",
"net/sched/cls_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"versionType": "git"
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{
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"status": "affected",
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{
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"product": "Linux",
"programFiles": [
"include/net/tc_act/tc_pedit.h",
"net/sched/act_api.c",
"net/sched/act_pedit.c",
"net/sched/cls_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.11"
},
{
"lessThan": "4.11",
"status": "unaffected",
"version": "0",
"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": "6.6.145",
"versionStartIncluding": "4.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
},
{
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}
],
"negate": false,
"operator": "OR"
}
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}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_pedit: fix TOCTOU heap OOB write in tc offload\n\nThere is a TOCTOU race condition in flower lockless approach between sizing\na flow_rule buffer and filling it.\nzdi-disclosures@trendmicro.com reports:\nThe cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED\n(fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the\nindependent locking domains make the race reachable in practice. KASAN\nconfirms:\n BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930\n Write of size 4 at addr ffff888001f27520 by task poc-toctou/312\n The buggy address is located 0 bytes to the right of\n allocated 288-byte region [ffff888001f27400, ffff888001f27520)\n (cache kmalloc-512)\n\nNote: The result is a heap OOB write attacker-controlled content into the\nadjacent slab object (requires CAP_NET_ADMIN).\n\nThe fix introduces reading tcfp_nkeys under act-\u003etcfa_lock in all places\nusing a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys().\nAdditionally we close the remaining TOCTOU window between the sizing read and\nthe fill reads by more careful accounting.\nRather than silently truncating the key count, which leads to incorrect\naction semantics offloaded to hardware and secondary OOB writes if\nthe remaining capacity is zero or consumed by prior actions, we enforce\nremaining capacity checks and return -ENOSPC if the required space exceeds\nthe remaining capacity."
}
],
"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 bug is reached only through rtnetlink TC APIs (RTM_NEWTFILTER cls_flower offload and RTM_NEWACTION pedit replace), not by processing remote network packets; per kernel guidance tc/qdisc/netlink paths are Local.\nAC:L - This is a TOCTOU race where the attacker runs both sides concurrently (flower filter hardware-offload setup vs RTM_NEWACTION REPLACE increasing pedit keys); Trend Micro reproduced it with task poc-toctou, so timing is attacker-driven not external.\nPR:L - All entry points require CAP_NET_ADMIN (rtnetlink checks netlink_net_capable); that capability is available to an unprivileged user who creates a user+network namespace (unshare -Urn), not only init-namespace root.\nUI:N - Exploitation needs no victim interaction; it is triggered entirely by the attacker\u0027s concurrent netlink configuration of pedit actions and cls_flower filters.\nS:U - Impact is kernel heap corruption and local privilege escalation within the same kernel security domain; it is not a VM escape, hypervisor bypass, or cross-authority sandbox breakout.\nC:H - KASAN reports a slab out-of-bounds write of attacker-controlled pedit mangle data into the adjacent kmalloc object; heap corruption of this kind is reasonably leveraged for kernel memory disclosure.\nI:H - The flaw is a heap out-of-bounds write (KASAN: write of size 4 past a 288-byte region) with attacker-chosen pedit key values, enabling heap grooming and potential control-flow hijack in kernel context.\nA:H - Corrupting adjacent slab objects during tc offload setup can cause immediate kernel oops/panic; KASAN already flags this as slab-out-of-bounds under concurrent offload activity."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:42:56.770Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/0d8532a5e972a5351cf4ee4a435e0d65cbba8f23"
},
{
"url": "https://git.kernel.org/stable/c/27488e1a7f19757e6146edca9458ed4ffc545557"
},
{
"url": "https://git.kernel.org/stable/c/6f9b23eb92a894ae1118893996943990ee0b860e"
},
{
"url": "https://git.kernel.org/stable/c/8e49cd891bda447c68122d672510a604a8bb6b24"
},
{
"url": "https://git.kernel.org/stable/c/8b519cbcabe836a441369fbec1a8a6518a709251"
}
],
"title": "net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-72338",
"datePublished": "2026-08-15T05:55:45.823Z",
"dateReserved": "2026-08-09T03:40:39.920Z",
"dateUpdated": "2026-08-17T05:42:56.770Z",
"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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