Linux Kernel keyctl_describe_key() UAF via key type name
CVE-2026-99224 Published on November 2, 2026
keys: Protect the type name while describing a key
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
Products Associated with CVE-2026-99224
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Affected Versions
Linux:- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below 19c4de819e52b7f606468fbfe4fcef4e812e2777 is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below a49e6c9a1a5b3457c946a8efb616ce13b4ca8194 is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below 916667df7695366f23cfaf365b5840b228cc4b2e is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below dddd3a1ab7d12ee163477918ff6eb943361db4fe is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below 3c3cfd9e262afc9558c38f8cec57f09d10988546 is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below 6b613747f7ea309ada5b8d05b55398c338f7a968 is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below dea367df18e3a4faac393e3a4e818ee03af89b19 is affected.
- Version aa9d4437893f7e015ce5b6d6c443a9ba92c8a2e7 and below 0461bc8f91116aae4a020e15f4e1c1fd535ab35e is affected.
- Version 3.18 is affected.
- Before 3.18 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.