CVE-2026-64439 Details
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.
A use-after-free vulnerability has been identified in the Linux kernel's implementation of Kerberos 5 cryptographic functions, specifically in the handling of asynchronous authenticated encryption with associated data (AEAD) operations. This issue arises in the 'crypto' subsystem, within the 'krb5' module, and affects several versions of the Linux kernel. The vulnerability occurs because the encryption and decryption functions for Kerberos 5, when bound to an asynchronous AEAD provider, can lead to a race condition. The functions 'krb5_aead_encrypt' and 'krb5_aead_decrypt' in 'rfc3961_simplified.c' and 'rfc8009_aes2.c' improperly manage completion callbacks and error handling. When an asynchronous AEAD instance is used, the request returns a 'in-progress' status, allowing the buffer to be freed while a backend worker still holds a pointer to it. This results in the worker dereferencing a freed memory slab, causing a use-after-free error. The vulnerability is reachable through specific network file system operations on systems with an asynchronous AEAD provider linked to the Kerberos 5 encryption type.
Users can upgrade to the latest stable version of the Linux kernel, where this vulnerability has been addressed. The specific commit that resolves this issue is included in the Linux kernel stable tree.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
No SSVC data is available for this CVE.
References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://git.kernel.org/stable/c/2b7bd6dccff14b8b632c5244f1fd506918077221 | kernel.org | Patch |
| https://git.kernel.org/stable/c/6c9dddeb582fde005360f4fe02c760d45ca05fb5 | kernel.org | Patch |
| https://git.kernel.org/stable/c/ef6feb77e2d91761427c5b773edc9c97e1b706ad | kernel.org | Patch |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-416 | Use After Free | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| linux linux kernel | >= 6.15, < 6.18.39 >= 6.19, < 7.1.4 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 3, 2026 | Initial Analysis | [email protected] |
| Aug 17, 2026 | CVE Modified | kernel.org |
| Jul 27, 2026 | CVE Modified | kernel.org |
| Jul 25, 2026 | New CVE Received | kernel.org |