Cloudanix VulnDB

CVE-2026-99225

None

CVSS

—

EPSS

0.2%

Published

Nov 2, 2026

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in how the Linux kernel manages security keys can make the whole computer crash without warning.

Exploitation
Local Privilege
Attacker needs
Low Privilege
Complexity
Moderate
Impact
Denial Of Service
Component
OS kernel
Class
Memory Corruption
Remediation
Patch
Effort
Medium
Patch risk
Low

What it actually does

A race condition in the Linux kernel key subsystem allows a NULL pointer dereference in search_process_keyrings_rcu() when an authorization payload is cleared during an RCU-protected search, resulting in a kernel oops.

Why it matters to the business

Can cause unexpected system crashes and kernel panics, leading to denial of service and potential data loss or corruption on affected systems.

How an attack unfolds

An attacker sets up a request-key authorization scenario with a helper process that forks a descendant. By carefully timing the invalidation of the authorization key during the descendant's keyring search under RCU, the attacker triggers the NULL dereference.

How to fix it

Update the Linux kernel to a version incorporating the fix that loads the payload via dereference_key_rcu() and requires a non-NULL result before validation and credential fallback.

How to confirm the fix worked

Inspect kernel source for the dereference_key_rcu() check and non-NULL payload guard in search_process_keyrings_rcu(); test for absence of the described KASAN null-ptr-deref oops under concurrent request-key scenarios.

Typical attack path

  1. Setup request key authorization with descendant process
  2. Trigger race by instantiating target key
  3. Cause descendant to dereference cleared payload
  4. Kernel crashes due to NULL pointer

How to detect it

Search kernel logs and crash dumps for general protection faults or null-ptr-deref reports referencing search_process_keyrings_rcu and KASAN payload handling.

  • search_process_keyrings_rcu+0x32b/0x790
  • KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
  • Oops: general protection fault, probably for non-canonical address

What your security team should do

  • Apply kernel updates immediately given the recent publication
  • Monitor kernel logs for oops and KASAN reports involving keyring searches
  • Limit unprivileged use of request-key helpers where feasible

The record

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

Affected packages

Ecosystem Package Introduced Fixed