CVE-2026-74255 (GCVE-0-2026-74255)
Vulnerability from cvelistv5
Published
2026-08-15 05:57
Modified
2026-08-17 05:45
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix UAF in tipc_l2_send_msg()
Syzbot reported a slab-use-after-free in ipvlan_hard_header() when
called from tipc_l2_send_msg().
The root cause is that tipc_disable_l2_media() calls synchronize_net()
while b->media_ptr is still valid. This allows concurrent RCU readers
to obtain the device pointer after synchronize_net() has finished.
The pointer is cleared later in bearer_disable(), but without any
subsequent synchronization, allowing the device to be freed while
still in use by readers.
Fix this by clearing b->media_ptr in tipc_disable_l2_media() before
calling synchronize_net().
This is safe to do now because the call order in bearer_disable()
was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic")
to call tipc_node_delete_links() (which needs the pointer) before
disable_media().
https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad Version: 282b3a056225b35024246f63feb91d769d714dad |
||
{
"containers": {
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"product": "Linux",
"programFiles": [
"net/tipc/bearer.c"
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
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"vendor": "Linux",
"versions": [
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"version": "4.4"
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.10.261",
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},
{
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"status": "unaffected",
"version": "5.15.212",
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},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
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},
{
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"status": "unaffected",
"version": "6.6.145",
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},
{
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"status": "unaffected",
"version": "6.12.97",
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},
{
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"status": "unaffected",
"version": "6.18.40",
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},
{
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"status": "unaffected",
"version": "7.1.5",
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},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
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}
],
"cpeApplicability": [
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"nodes": [
{
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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\ntipc: fix UAF in tipc_l2_send_msg()\n\nSyzbot reported a slab-use-after-free in ipvlan_hard_header() when\ncalled from tipc_l2_send_msg().\n\nThe root cause is that tipc_disable_l2_media() calls synchronize_net()\nwhile b-\u003emedia_ptr is still valid. This allows concurrent RCU readers\nto obtain the device pointer after synchronize_net() has finished.\nThe pointer is cleared later in bearer_disable(), but without any\nsubsequent synchronization, allowing the device to be freed while\nstill in use by readers.\n\nFix this by clearing b-\u003emedia_ptr in tipc_disable_l2_media() before\ncalling synchronize_net().\n\nThis is safe to do now because the call order in bearer_disable()\nwas reversed in 0d051bf93c06 (\"tipc: make bearer packet filtering generic\")\nto call tipc_node_delete_links() (which needs the pointer) before\ndisable_media().\n\nhttps: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - tipc_l2_send_msg is reached from tipc_bearer_xmit during L2 TIPC protocol handling; remote ETH_P_TIPC frames on cluster/datacenter L2 networks drive outbound transmission that races with bearer teardown in tipc_disable_l2_media.\nAC:L - The UAF window is a race where attackers control both sides by flooding TIPC Ethernet traffic while bearer disable runs and by concurrently triggering bearer teardown; syzbot reliably reproduced this without attacker-uncontrollable timing.\nPR:N - An unauthenticated remote attacker only needs to send TIPC L2 frames on a segment with an active bearer; bearer_disable teardown during cluster failover, netdev unregister, or node shutdown creates the required concurrent disable without attacker-local privileges.\nUI:N - No victim user action is required; exploitation is triggered by remote protocol traffic concurrent with automated or administrative bearer/interface teardown events.\nS:U - Impact is kernel slab memory corruption and potential privilege escalation within the same kernel security boundary, not a cross-VM or cross-namespace escape.\nC:H - Slab use-after-free of a net_device structure via ipvlan_hard_header enables reading freed kernel heap memory and can be leveraged for arbitrary kernel memory disclosure.\nI:H - UAF on net_device during dev_hard_header allows heap grooming and control of freed object contents, enabling arbitrary kernel writes and potential code execution.\nA:H - The UAF causes kernel oops/panic (as reported by syzbot in ipvlan_hard_header) and can be triggered repeatedly to deny service on cluster nodes."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:45:03.215Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/609ced2301be1df7e7ed2ef47d1d916674e6ba3b"
},
{
"url": "https://git.kernel.org/stable/c/71aafa16d79b107b33837f60b6cbc7d0cb8c5708"
},
{
"url": "https://git.kernel.org/stable/c/f4002f1c669cc02e3763f479fc25ff1dfa9e2420"
},
{
"url": "https://git.kernel.org/stable/c/50ff092633b06382e5091dd5b093ce943d4ac2f9"
},
{
"url": "https://git.kernel.org/stable/c/aef12b5ce793dea6b3a97a58fd0f946000ae8945"
},
{
"url": "https://git.kernel.org/stable/c/0d8a12d7143126afdf9fbe2e3d438650dd6603ed"
},
{
"url": "https://git.kernel.org/stable/c/35e0297a93c3c34a3924eeef816c03504e3ab5c5"
},
{
"url": "https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6"
}
],
"title": "tipc: fix UAF in tipc_l2_send_msg()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74255",
"datePublished": "2026-08-15T05:57:34.293Z",
"dateReserved": "2026-08-15T05:44:03.876Z",
"dateUpdated": "2026-08-17T05:45:03.215Z",
"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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