SEPTEMBER 17, 2026
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Case File

CVE-2026-64439

CRITICAL · CVSS 9.8 EPSS 0.43%

Source: NVD + CISA KEV + EPSS · Published 2026-07-25 · Last synced 2026-08-24

CyberRota Analysis

AI-Generated

The vulnerability affects the Linux kernel's krb5 encryption functions, specifically in how they handle asynchronous AEAD implementations, leading to a use-after-free condition. This flaw can result in potential remote code execution or system crashes when the buffer is improperly freed while still in use by a worker thread. Organizations using Linux systems with asynchronous AEAD providers should prioritize patching this critical vulnerability to mitigate the risk of exploitation.

CVE
CVE-2026-64439
Severity
CRITICAL
CVSS
9.8
EPSS
0.43%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead implementations at alloc krb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and rfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL completion callback and treat any negative return from crypto_aead_{encrypt,decrypt}() as terminal, falling through to kfree_sensitive(buffer). When the encrypt_name resolves to an async AEAD instance the request returns -EINPROGRESS, the buffer is freed while the backend's worker still holds a pointer, and the worker dereferences the freed slab on completion. KASAN report under UML+SLUB with a synthetic async aead backend bound to krb5->encrypt_name: BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7 The helpers were written synchronously, so filter the async instances out at allocation time instead of plumbing crypto_wait_req() through every call site. Reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and net/ceph/crypto.c on systems with an async AEAD provider bound to the krb5 enctype name.