KEYS: Fix add_key() race with keyring restriction
Summary
| CVE | CVE-2026-99040 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-23 13:17:27 UTC |
| Updated | 2026-10-30 13:21:41 UTC |
| 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. |
Risk And Classification
EPSS: 0.001910000 probability, percentile 0.087730000 (date 2026-11-01)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c 24806fc9bca28fa1433bf938d1424dcb45d80e50 git | Not specified |
| CNA | Linux | Linux | affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c 9a5c2700336878465a630804a2d21864f22eca9c git | Not specified |
| CNA | Linux | Linux | affected 5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c b3e404550dc2b7f3d4bb64b1da8005a1fa9a798d git | Not specified |
| 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 5.10.273 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.224 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.191 6.1.* 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/24806fc9bca28fa1433bf938d1424dcb45d80e50 | 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 | |
| git.kernel.org/stable/c/9a5c2700336878465a630804a2d21864f22eca9c | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/b3e404550dc2b7f3d4bb64b1da8005a1fa9a798d | 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.