KEYS: Fix add_key() race with keyring restriction
Summary
| CVE | CVE-2026-99040 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-10-23 13:17:27 UTC |
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| Updated | 2026-10-23 13:17:27 UTC |
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| 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. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c 305f1828b871dd46bf41addeb6f11d2c162dcb25 git |
Not specified |
| CNA |
Linux |
Linux |
affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c f99399b48e3edd6851fac34cd329bab9f1f33baf git |
Not specified |
| CNA |
Linux |
Linux |
affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c 11516a0c402a6c1fa52254aa70d8d65fb921e59e git |
Not specified |
| CNA |
Linux |
Linux |
affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c da0b595d8e6e2dd798f6e34e09dc51a13b888514 git |
Not specified |
| CNA |
Linux |
Linux |
affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c dd3ea3fcba7c75493760cdbccd35f029597e8d5e git |
Not specified |
| CNA |
Linux |
Linux |
affected 4.7 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 4.7 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.6.160 6.6.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.113 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.57 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.11 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/11516a0c402a6c1fa52254aa70d8d65fb921e59e |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/da0b595d8e6e2dd798f6e34e09dc51a13b888514 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.