Linux Kernel NULL Deref via Keyring Misauthorization (CVE-2026-99225)
CVE-2026-99225 Published on November 2, 2026
keys: Check the authorization payload in process keyring searches
In the Linux kernel, the following vulnerability has been resolved:
keys: Check the authorization payload in process keyring searches
An authorization payload and its saved credentials must remain valid
while search_process_keyrings_rcu() searches the requestor's keyrings.
The function validates the authorization key, then separately loads
payload.data[0] and unconditionally reads rka->cred. Validation does
not prevent request_key_auth_revoke() from clearing the payload.
A request-key helper can assume authority and fork a descendant that
inherits the authorization key. If the descendant misses in its own
keyrings, it falls back to the saved requestor credentials. Successful
target instantiation invalidates the authorization key without clearing
the payload. After the helper exits, UMH_WAIT_PROC returns to the
requester, which calls complete_request_key() and revokes that key.
With the descendant paused after validation, the paths can interleave
as follows:
1. The descendant enters search_process_keyrings_rcu() under RCU and
key_validate() succeeds.
2. The helper instantiates the target, invalidates the authorization
key, and exits.
3. The requester resumes from UMH_WAIT_PROC, calls
complete_request_key(), and revokes the authorization key.
request_key_auth_revoke() sets its payload pointer to NULL.
4. The descendant loads NULL and dereferences rka->cred.
This NULL dereference can oops the kernel. RCU delays payload disposal
but does not prevent the pointer from being cleared.
Load the payload with dereference_key_rcu() and require a non-NULL
result before validating the authorization key and searching its saved
credentials. A non-NULL payload and its credentials remain alive for
the caller's RCU read-side section; a cleared payload skips the fallback
search and follows the existing error selection.
KASAN report as below:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
RIP: 0010:search_process_keyrings_rcu+0x32b/0x790
Products Associated with CVE-2026-99225
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Affected Versions
Linux:- Version e59428f721ee096d8a020504ea908a6f0d952735 and below 14fb6fad526b35a7ebd121f1dd313abe652e0aa6 is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below 458cf9715af6aff3ac8d2ec60bd59e9d6236fd0f is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below 7d3d2fffe933e538472ccafe5bbc7109488b9ce3 is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below 26949c2e4c461e9e620e935bc22717f36a40b615 is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below 984a178d54515779a1bee100b92a6cee8777c830 is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below b86db7993051d05810601654e886a1e78e1fa495 is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below b4dfda438fee3c6faa15d9b421c373de6a0e476f is affected.
- Version e59428f721ee096d8a020504ea908a6f0d952735 and below 49f4e768540d25d8852ef750313afda6a4774871 is affected.
- Version 5.3 is affected.
- Before 5.3 is unaffected.
- Version 5.10.273, <= 5.10.* is unaffected.
- Version 5.15.224, <= 5.15.* is unaffected.
- Version 6.1.191, <= 6.1.* is unaffected.
- Version 6.6.161, <= 6.6.* is unaffected.
- Version 6.12.115, <= 6.12.* is unaffected.
- Version 6.18.60, <= 6.18.* is unaffected.
- Version 7.2.14, <= 7.2.* is unaffected.
- Version 7.3.1, <= 7.3.* is unaffected.