Linux Kernel up to 6.18.38/7.1.3 Crypto rfc3961_simplified.c use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k2.33-

Summaryinfo

A vulnerability described as very critical has been identified in Linux Kernel up to 6.18.38/7.1.3. Impacted is the function krb5_aead_encrypt/krb5_aead_decrypt/rfc8009_encrypt/rfc8009_decrypt of the file rfc3961_simplified.c of the component Crypto. Such manipulation leads to use after free. This vulnerability is traded as CVE-2026-64439. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.38/7.1.3 and classified as very critical. Affected by this issue is the function krb5_aead_encrypt/krb5_aead_decrypt/rfc8009_encrypt/rfc8009_decrypt of the file rfc3961_simplified.c of the component Crypto. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-64439 since 07/19/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 07/25/2026).

Upgrading to version 6.18.39, 7.1.4 or 7.2-rc1 eliminates this vulnerability. Applying the patch ef6feb77e2d91761427c5b773edc9c97e1b706ad/2b7bd6dccff14b8b632c5244f1fd506918077221/6c9dddeb582fde005360f4fe02c760d45ca05fb5 is able to eliminate this problem.

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Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.39/7.1.4/7.2-rc1
Patch: ef6feb77e2d91761427c5b773edc9c97e1b706ad/2b7bd6dccff14b8b632c5244f1fd506918077221/6c9dddeb582fde005360f4fe02c760d45ca05fb5

Timelineinfo

07/19/2026 CVE reserved
07/25/2026 +6 days Advisory disclosed
07/25/2026 +0 days VulDB entry created
07/25/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-64439 (🔒)
GCVE (CVE): GCVE-0-2026-64439
GCVE (VulDB): GCVE-100-383234

Entryinfo

Created: 07/25/2026 18:44
Changes: 07/25/2026 18:44 (60)
Complete: 🔍
Cache ID: 216::103

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