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libkcapi EUVDEUVD-2026-53337

| CVE-2026-71227 MEDIUM
Loop with Unreachable Exit Condition (Infinite Loop) (CWE-835)
2026-08-05 redhat GHSA-c5mv-c5vm-62w5
Denial Of Service Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Openshift Container Platform 4 Red Hat Hardened Images Red Hat
5.1
CVSS 3.1 · NVD
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Severity by source

Vendor (redhat) PRIMARY
MEDIUM
qualitative
NVD
5.1 MEDIUM
AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.1 MEDIUM

Local-only attack requiring specific AIO error-state conditions (AC:H); no OS privileges needed; purely availability impact with no scope change.

3.1 AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat
5.1 MEDIUM
qualitative

Primary rating from Vendor (redhat).

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
CVSS changed
Aug 11, 2026 - 18:22 NVD
5.5 (MEDIUM) 5.1 (MEDIUM)
CVSS changed
Aug 11, 2026 - 17:52 NVD
5.1 (MEDIUM) 5.5 (MEDIUM)
Analysis Generated
Aug 05, 2026 - 13:54 vuln.today
CVE Published
Aug 05, 2026 - 12:42 nvd
MEDIUM 5.1

DescriptionNVD

A flaw was found in libkcapi. A local attacker can influence an application that uses the Asynchronous Input/Output (AIO) interface. By reusing an AIO-enabled handle after a prior completion error, the _kcapi_aio_read_all() function can enter a non-terminating wait loop. This can lead to a persistent denial of service, making the affected application or thread unresponsive.

AnalysisAI

Persistent denial of service in libkcapi's AIO interface allows a local attacker to permanently hang an affected application thread by exploiting improper error-state handling in _kcapi_aio_read_all(). Affected deployments span Red Hat Enterprise Linux 8, 9, and 10, Red Hat Hardened Images, and Red Hat OpenShift Container Platform 4 - all environments where applications leverage libkcapi's asynchronous cryptographic operations. No public exploit code or active exploitation has been identified at time of analysis; the high attack complexity (AC:H) and local-only attack vector substantially limit real-world risk beyond targeted or insider-threat scenarios.

Technical ContextAI

libkcapi is a userspace C library that wraps the Linux kernel's AF_ALG (Algorithm) socket interface, enabling applications to offload symmetric encryption, hashing, and other cryptographic operations to the kernel without requiring direct system call management. The AIO (Asynchronous I/O) path in libkcapi uses the kernel's io_submit/io_getevents mechanism to process crypto requests non-blocking. CWE-835 (Loop with Unreachable Exit Condition) identifies the root cause: _kcapi_aio_read_all() does not validate or reset the handle's internal state after a prior completion error, causing it to enter an infinite polling loop waiting for a completion event that the errored handle will never deliver. This is a pure logic flaw in error-state lifecycle management - not a memory corruption issue - affecting the CPE-confirmed products cpe:2.3:a:red_hat:red_hat_enterprise_linux_8 through rhel_10, red_hat_hardened_images, and openshift_container_platform_4.

RemediationAI

Apply Red Hat-issued errata for the libkcapi package once available, as documented at https://access.redhat.com/security/cve/CVE-2026-71227. No exact fixed package version was confirmed in the provided data - consult the Red Hat advisory and associated Bugzilla entry (https://bugzilla.redhat.com/show_bug.cgi?id=2462867) for specific errata identifiers. As a compensating control pending a patch, restrict local user access to processes that use libkcapi's AIO interface using SELinux mandatory access controls or cgroup-based process isolation, which limits which users can interact with or signal crypto-enabled applications - this does not eliminate the vulnerability but raises the attacker bar. Application developers using libkcapi should audit all call sites of _kcapi_aio_read_all() to ensure AIO handles are explicitly closed and re-initialized after any completion error rather than reused. Migrating affected applications to libkcapi's synchronous API as a temporary measure eliminates the AIO-specific code path entirely, at the cost of blocking I/O behavior.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Not-Affected
SUSE Linux Enterprise Micro 5.3 Not-Affected
SUSE Linux Enterprise Micro 5.4 Not-Affected
SUSE Linux Enterprise Micro 5.5 Not-Affected

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EUVD-2026-53337 vulnerability details – vuln.today
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