CVE-2026-99040
Full vulnerability record from the local CVENow database.
Description
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.
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-10-23 13:17:27.360000
Last modified
2026-10-30 13:21:41.200000
View original CVE JSON
{
"id": "CVE-2026-99040",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-23T13:17:27.360",
"lastModified": "2026-10-30T13:21:41.200",
"vulnStatus": "Received",
"cveTags": [],
"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->restrict_link before taking\nthe destination keyring's 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->sem.\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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"security/keys/key.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
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"versions": [
{
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"status": "affected"
},
{
"version": "0",
"lessThan": "4.7",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.273",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.224",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.160",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.113",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.57",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.11",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
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