CVE-2026-68338 (GCVE-0-2026-68338)
Vulnerability from cvelistv5
Published
2026-08-10 12:03
Modified
2026-08-19 16:33
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/packet: avoid fanout hook re-registration after unregister
packet_set_ring() temporarily detaches a socket from packet delivery while
reconfiguring its ring. It records the previous running state, clears
po->num, unregisters the protocol hook when needed, drops po->bind_lock,
and later restores po->num and re-registers the hook from the saved
was_running value.
That unlocked window can race with NETDEV_UNREGISTER. The notifier can
observe the socket as not running, skip __unregister_prot_hook(), and
invalidate the per-socket binding by setting po->ifindex to -1 and clearing
po->prot_hook.dev. A one-member fanout group can still retain its shared
fanout hook device pointer. When packet_set_ring() resumes, re-registering
solely from the stale was_running state can re-add the fanout hook after
the device has been unregistered.
Treat po->ifindex == -1 as an invalidated binding after reacquiring
po->bind_lock. This is distinct from ifindex 0, the normal
unbound/wildcard state: ifindex -1 marks an existing device binding that
was invalidated when the device was unregistered. Restore po->num as
before, but do not re-register the hook if device unregister already
detached the socket.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc Version: dc99f600698dcac69b8f56dda9a8a00d645c5ffc |
||
{
"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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"status": "affected",
"version": "dc99f600698dcac69b8f56dda9a8a00d645c5ffc",
"versionType": "git"
},
{
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"status": "affected",
"version": "dc99f600698dcac69b8f56dda9a8a00d645c5ffc",
"versionType": "git"
},
{
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"status": "affected",
"version": "dc99f600698dcac69b8f56dda9a8a00d645c5ffc",
"versionType": "git"
},
{
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{
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{
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{
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"versionType": "git"
},
{
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"status": "affected",
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]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/packet/af_packet.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.1"
},
{
"lessThan": "3.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.148",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.6",
"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": "5.10.265",
"versionStartIncluding": "3.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "3.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.101",
"versionStartIncluding": "3.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.42",
"versionStartIncluding": "3.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.6",
"versionStartIncluding": "3.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "3.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: avoid fanout hook re-registration after unregister\n\npacket_set_ring() temporarily detaches a socket from packet delivery while\nreconfiguring its ring. It records the previous running state, clears\npo-\u003enum, unregisters the protocol hook when needed, drops po-\u003ebind_lock,\nand later restores po-\u003enum and re-registers the hook from the saved\nwas_running value.\n\nThat unlocked window can race with NETDEV_UNREGISTER. The notifier can\nobserve the socket as not running, skip __unregister_prot_hook(), and\ninvalidate the per-socket binding by setting po-\u003eifindex to -1 and clearing\npo-\u003eprot_hook.dev. A one-member fanout group can still retain its shared\nfanout hook device pointer. When packet_set_ring() resumes, re-registering\nsolely from the stale was_running state can re-add the fanout hook after\nthe device has been unregistered.\n\nTreat po-\u003eifindex == -1 as an invalidated binding after reacquiring\npo-\u003ebind_lock. This is distinct from ifindex 0, the normal\nunbound/wildcard state: ifindex -1 marks an existing device binding that\nwas invalidated when the device was unregistered. Restore po-\u003enum as\nbefore, but do not re-register the hook if device unregister already\ndetached the socket."
}
],
"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 triggered through local syscalls \u2014 creating an AF_PACKET socket, PACKET_FANOUT/bind setsockopt, PACKET_RX_RING setsockopt, and a netlink device unregister \u2014 with no remote packet processing involved.\nAC:L - The attacker controls both sides of the race: it issues the packet_set_ring() reconfiguration and deletes the bound netdev in its own netns, and the unlocked window spans synchronize_net() plus the ring swap, making it wide and reliably winnable.\nPR:L - AF_PACKET requires CAP_NET_RAW and device unregistration CAP_NET_ADMIN, but an unprivileged user obtains both via user+network namespaces (unshare -Urn) and can create and delete veth/dummy devices there.\nUI:N - The attacker performs every step itself \u2014 socket setup, ring reconfiguration and device teardown \u2014 with no action required from any other user.\nS:U - The stale hook registration and resulting corruption stay within the kernel\u0027s own security authority; no hypervisor, IOMMU or other trust boundary is crossed.\nC:H - The fanout packet_type is left linked into a net_device that is being torn down, a dangling registration on soon-to-be-freed memory; such stale-pointer state in the ptype lists can be leveraged for kernel memory disclosure.\nI:H - The dangling list node in the freed net_device\u0027s ptype list yields a list_del write into freed memory when the hook is later removed, a controllable write primitive typical of use-after-free exploitation.\nA:H - The re-added hook makes netdev_run_todo() hit BUG_ON(!list_empty(\u0026dev-\u003eptype_all)) while RTNL is held, oopsing the kernel and permanently wedging all further network configuration \u2014 a repeatable, unprivileged host-wide denial of service."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:33:38.308Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/acb40ebfa5c4d62f84339fcbf713f2a9fd033a71"
},
{
"url": "https://git.kernel.org/stable/c/c820f4b7f2fa38f8769db0d0cefdd94e2721504d"
},
{
"url": "https://git.kernel.org/stable/c/4628efbdc7affd094181f5263e65c1062e31f15f"
},
{
"url": "https://git.kernel.org/stable/c/80ec024d53a05c60ad1d08968dcf745f10c1665c"
},
{
"url": "https://git.kernel.org/stable/c/0a052e0808e015e68144a9877e6ef42b952c49fa"
},
{
"url": "https://git.kernel.org/stable/c/1bc55c29cd85818e9052f17deb287d5a11fb817f"
},
{
"url": "https://git.kernel.org/stable/c/a885387dae7986a55bae5c77a15bdd447f64e9b9"
},
{
"url": "https://git.kernel.org/stable/c/50aff80475abd3533eef4320477037e6fcc6b56e"
}
],
"title": "net/packet: avoid fanout hook re-registration after unregister",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-68338",
"datePublished": "2026-08-10T12:03:14.549Z",
"dateReserved": "2026-07-30T09:28:09.384Z",
"dateUpdated": "2026-08-19T16:33:38.308Z",
"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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