CVE-2026-99040 (GCVE-0-2026-99040)
Vulnerability from cvelistv5
Published
2026-10-23 12:21
Modified
2026-10-30 12:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
KEYS: Fix add_key() race with keyring restriction
__key_create_or_update() snapshots keyring->restrict_link before taking
the destination keyring's semaphore. keyring_restrict() installs a
restriction while holding that semaphore.
This allows a writer to observe no restriction, wait for the keyring
owner to install a reject-all restriction and return successfully, and
then link a key using the stale NULL snapshot. The writer only needs
write permission on the destination keyring.
Move the restrict_link read after __key_link_lock() and
__key_link_begin(). The read and the subsequent restriction check are
then serialized with restriction installation by keyring->sem.
The race was reproduced on v7.2.8 in 19 executions where restriction
installation returned before the link completed. All 19 linked the key
despite the reject-all restriction. With this change, 312 executions
reached the same ordering and every add_key() call failed with -EPERM.
The issue was found by manual concurrency analysis assisted by AI-based
analysis and independently verified with a QEMU reproducer and kernel
instrumentation.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c Version: 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c |
||
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: Fix add_key() race with keyring restriction\n\n__key_create_or_update() snapshots keyring-\u003erestrict_link before taking\nthe destination keyring\u0027s semaphore. keyring_restrict() installs a\nrestriction while holding that semaphore.\n\nThis allows a writer to observe no restriction, wait for the keyring\nowner to install a reject-all restriction and return successfully, and\nthen link a key using the stale NULL snapshot. The writer only needs\nwrite permission on the destination keyring.\n\nMove the restrict_link read after __key_link_lock() and\n__key_link_begin(). The read and the subsequent restriction check are\nthen serialized with restriction installation by keyring-\u003esem.\n\nThe race was reproduced on v7.2.8 in 19 executions where restriction\ninstallation returned before the link completed. All 19 linked the key\ndespite the reject-all restriction. With this change, 312 executions\nreached the same ordering and every add_key() call failed with -EPERM.\n\nThe issue was found by manual concurrency analysis assisted by AI-based\nanalysis and independently verified with a QEMU reproducer and kernel\ninstrumentation."
}
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"providerMetadata": {
"dateUpdated": "2026-10-30T12:41:13.694Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"url": "https://git.kernel.org/stable/c/24806fc9bca28fa1433bf938d1424dcb45d80e50"
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"url": "https://git.kernel.org/stable/c/9a5c2700336878465a630804a2d21864f22eca9c"
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{
"url": "https://git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25"
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{
"url": "https://git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf"
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{
"url": "https://git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e"
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],
"title": "KEYS: Fix add_key() race with keyring restriction",
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"cveId": "CVE-2026-99040",
"datePublished": "2026-10-23T12:21:59.288Z",
"dateReserved": "2026-09-25T10:25:14.387Z",
"dateUpdated": "2026-10-30T12:41:13.694Z",
"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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