CVE-2026-74543 (GCVE-0-2026-74543)
Vulnerability from cvelistv5
Published
2026-08-15 12:27
Modified
2026-08-17 05:21
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()
syzbot reported a memory leak [1] in the UDP tunnel NIC offload code.
When device registration fails (e.g. in register_netdevice()), netdev core
unwinds by sending a single NETDEV_UNREGISTER notification. If work was queued
during NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister()
returns early:
if (utn->work_pending)
return;
Because failed registrations do not enter netdev_wait_allrefs_any(), no
subsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the
struct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked
permanently.
Fix this by removing the early return. Instead, synchronously cancel any
pending work with cancel_delayed_work_sync() before freeing @utn.
To be able to call cancel_delayed_work_sync() while holding RTNL (the work also
needs RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL
is contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())
to prevent high CPU contention while waiting for RTNL lock.
The utn->work_pending bookkeeping is no longer needed and is removed, as
the workqueue core already tracks the pending/running state of the work.
[1]
BUG: memory leak
unreferenced object 0xffff888127d5f840 (size 96):
comm "syz-executor", pid 5806, jiffies 4294942188
backtrace (crc 99fdb6c8):
__kmalloc_noprof+0x3bf/0x550
udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]
udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]
udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931
notifier_call_chain+0x59/0x160 kernel/notifier.c:85
call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250
register_netdevice+0xc10/0xeb0 net/core/dev.c:11478
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/udp_tunnel_nic.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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"status": "affected",
"version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
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"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.9"
},
{
"lessThan": "5.9",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.103",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.44",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.8",
"versionType": "semver"
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{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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"nodes": [
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"versionEndExcluding": "6.12.103",
"versionStartIncluding": "5.9",
"vulnerable": true
},
{
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{
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()\n\nsyzbot reported a memory leak [1] in the UDP tunnel NIC offload code.\n\nWhen device registration fails (e.g. in register_netdevice()), netdev core\nunwinds by sending a single NETDEV_UNREGISTER notification. If work was queued\nduring NETDEV_REGISTER (utn-\u003ework_pending is set), udp_tunnel_nic_unregister()\nreturns early:\n\n\tif (utn-\u003ework_pending)\n\t\treturn;\n\nBecause failed registrations do not enter netdev_wait_allrefs_any(), no\nsubsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the\nstruct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked\npermanently.\n\nFix this by removing the early return. Instead, synchronously cancel any\npending work with cancel_delayed_work_sync() before freeing @utn.\n\nTo be able to call cancel_delayed_work_sync() while holding RTNL (the work also\nneeds RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL\nis contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())\nto prevent high CPU contention while waiting for RTNL lock.\n\nThe utn-\u003ework_pending bookkeeping is no longer needed and is removed, as\nthe workqueue core already tracks the pending/running state of the work.\n\n[1]\nBUG: memory leak\nunreferenced object 0xffff888127d5f840 (size 96):\n comm \"syz-executor\", pid 5806, jiffies 4294942188\n backtrace (crc 99fdb6c8):\n __kmalloc_noprof+0x3bf/0x550\n udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]\n udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]\n udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931\n notifier_call_chain+0x59/0x160 kernel/notifier.c:85\n call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250\n register_netdevice+0xc10/0xeb0 net/core/dev.c:11478"
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:21:28.314Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b712da45bd9b9835d132e9fbc0c3e43c164cb1fd"
},
{
"url": "https://git.kernel.org/stable/c/f82a2ded3d7a9098267c84f14eafdb98c4550ac5"
},
{
"url": "https://git.kernel.org/stable/c/b322532a4b774db1b480a2de84125910a70739a5"
},
{
"url": "https://git.kernel.org/stable/c/080695e6f005e2396f1207fd69d24c442cb230c6"
}
],
"title": "net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74543",
"datePublished": "2026-08-15T12:27:53.336Z",
"dateReserved": "2026-08-15T05:44:03.914Z",
"dateUpdated": "2026-08-17T05:21:28.314Z",
"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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