CVE-2026-99054 (GCVE-0-2026-99054)
Vulnerability from cvelistv5
Published
2026-10-23 12:22
Modified
2026-10-30 12:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
tipc: destroy topsrv workqueues before closing connections
tipc_topsrv_stop() closed subscriber connections while the topology
server's send and receive workqueues were still running. Socket
callbacks and subscription events could then queue more work, and
in-flight send/recv work could drop the last connection reference
during the conn_idr walk.
That race produced several teardown failures: refcount_t addition on
0 from conn_get() on a connection whose release was blocked on
idr_lock, a subsequent use-after-free in tipc_conn_close(),
queue_work() on an already destroyed workqueue from the listener
data-ready callback, and an RCU stall in tipc_topsrv_exit_net()
while the walk spun under idr_lock.
Clear srv->listener under idr_lock so it acts as a shutdown flag,
skip queue_work() once it is NULL, destroy the workqueues to flush
in-flight work, and only then close the remaining connections.
Refuse tipc_conn_lookup() after that flag is cleared, and drop
idr_lock when the teardown walk finds no connection, so an
in-flight subscription event cannot pin idr_in_use while the
walk holds the lock.
v3 supersedes the narrower in-thread diff Tung Quang Nguyen
posted on 2026-09-23. It keeps his teardown order and adds the
lookup refusal and the empty-idr unlock.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f Version: c5fa7b3cf3cb22e4ac60485fc2dc187fe012910f |
||
{
"containers": {
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{
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"product": "Linux",
"programFiles": [
"net/tipc/topsrv.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"vendor": "Linux",
"versions": [
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"status": "unaffected",
"version": "0",
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},
{
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"status": "unaffected",
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{
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"status": "unaffected",
"version": "5.15.224",
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},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.191",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.6.160",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.12.113",
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},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.11",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"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: destroy topsrv workqueues before closing connections\n\ntipc_topsrv_stop() closed subscriber connections while the topology\nserver\u0027s send and receive workqueues were still running. Socket\ncallbacks and subscription events could then queue more work, and\nin-flight send/recv work could drop the last connection reference\nduring the conn_idr walk.\n\nThat race produced several teardown failures: refcount_t addition on\n0 from conn_get() on a connection whose release was blocked on\nidr_lock, a subsequent use-after-free in tipc_conn_close(),\nqueue_work() on an already destroyed workqueue from the listener\ndata-ready callback, and an RCU stall in tipc_topsrv_exit_net()\nwhile the walk spun under idr_lock.\n\nClear srv-\u003elistener under idr_lock so it acts as a shutdown flag,\nskip queue_work() once it is NULL, destroy the workqueues to flush\nin-flight work, and only then close the remaining connections.\nRefuse tipc_conn_lookup() after that flag is cleared, and drop\nidr_lock when the teardown walk finds no connection, so an\nin-flight subscription event cannot pin idr_in_use while the\nwalk holds the lock.\n\nv3 supersedes the narrower in-thread diff Tung Quang Nguyen\nposted on 2026-09-23. It keeps his teardown order and adds the\nlookup refusal and the empty-idr unlock."
}
],
"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 - `unshare(CLONE_NEWUSER|CLONE_NEWNET)` creates the per-net TIPC server; local `socket(AF_TIPC)`, `connect(TIPC_TOP_SRV)`, and `send()` churn followed by exit drives `cleanup_net()` -\u003e `tipc_topsrv_exit_net()` -\u003e patched `tipc_topsrv_stop()`. No remote message can cause the required namespace teardown.\nAC:L - The attacker controls both sides of the race: worker threads repeatedly create and close topology subscriptions while their process exits the network namespace, racing `rwork`/`swork` and socket callbacks against `tipc_topsrv_stop()`. No victim or hardware state is required.\nPR:L - `tipc_sk_create()`, `tipc_connect()`, and `tipc_conn_rcv_sub()` have no capability or authentication gate; an ordinary user can obtain the `CAP_SYS_ADMIN` needed for `CLONE_NEWNET` inside a new user namespace. No init-namespace privilege is required.\nUI:N - The attacker creates the namespaces, opens and floods `TIPC_TOP_SRV` connections, closes them, and exits to start `cleanup_net()` without any victim action.\nS:U - The freed `tipc_conn` and workqueue objects belong to the host kernel, and exploitation of `tipc_topsrv_stop()` affects that same kernel authority without crossing a VM, IOMMU, or other security boundary.\nC:H - `tipc_conn_kref_release()` frees `con` while teardown retains its address; `tipc_conn_close()` then reads `con-\u003esock-\u003esk` and follows reclaimed subscription and socket pointers. Reclaiming this object permits attacker-controlled pointer dereferences usable as kernel-memory read primitives.\nI:H - After the free, `tipc_conn_close()` modifies reclaimed `con-\u003eflags`, writes through `sk-\u003esk_user_data`, processes reclaimed subscription lists, and calls `kernel_sock_shutdown()` through `con-\u003esock-\u003eops`. These provide memory-write and control-flow primitives.\nA:H - The reported race produced a page fault in `tipc_conn_close()`, `queue_work()` on a destroyed receive workqueue, and an RCU stall in `tipc_topsrv_exit_net()`; these paths can oops, panic, or wedge the system."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:41:21.256Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/09dbd610f78aaed65d7b379c270ce4090a8151ac"
},
{
"url": "https://git.kernel.org/stable/c/21622e5ae8b232c2e64eb1adf5546cf078d2987d"
},
{
"url": "https://git.kernel.org/stable/c/7167afaaaee37191f8b6afa0c91e0fef41460705"
},
{
"url": "https://git.kernel.org/stable/c/7f796bb3b440d7f1b14c0e3b520462eb34f553af"
},
{
"url": "https://git.kernel.org/stable/c/da9c16568bc79140a54c1f5fcf07a0305df47b37"
},
{
"url": "https://git.kernel.org/stable/c/0af8780bdfdfc91fb9127bddb9c48fab67dc9d9e"
},
{
"url": "https://git.kernel.org/stable/c/fb717c536af2aafeca520ff11d1e0f25f7ab8fa9"
},
{
"url": "https://git.kernel.org/stable/c/3acdd44385bc7e2e57605e073691ce69cc5a960d"
}
],
"title": "tipc: destroy topsrv workqueues before closing connections",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-99054",
"datePublished": "2026-10-23T12:22:36.886Z",
"dateReserved": "2026-09-25T10:25:14.388Z",
"dateUpdated": "2026-10-30T12:41:21.256Z",
"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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