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Fencer Vulns
medium 5.1

CVE-2026-71227 json

Libkcapi: infinite loop denial of service in libkcapi _kcapi_aio_read_all() due to unhandled io_getevents() timeout return

published 2026-08-05 3 mo ago modified 2026-11-02 7 d ago also EUVD-2026-53337

cvss
5.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

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.

Patch / fix

  • Stephan Muelle libkcapi 1.5.1
  • Red Hat Red Hat Enterprise Linux 10 0:1.5.1-1.el10_2
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:1.5.0-6.el10_0
  • Red Hat Red Hat Enterprise Linux 8 0:1.4.0-3.el8_10
  • Red Hat Red Hat Enterprise Linux 9 0:1.4.0-3.el9_8
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:1.4.0-2.el9_6.1
  • Red Hat Red Hat Hardened Images 1.5.1-0.1.hum1
  • libkcapi Debian 14 1.5.1-1

debian advisories DEBIAN-CVE-2026-71227

  • libkcapi RHEL 8 1.4.0-3.el8_10
  • libkcapi-hmaccalc RHEL 8 1.4.0-3.el8_10
  • libkcapi RHEL 10.2 1.5.1-1.el10_2
  • libkcapi-hasher RHEL 10.2 1.5.1-1.el10_2
  • libkcapi-hmaccalc RHEL 10.2 1.5.1-1.el10_2
  • libkcapi RHEL 9 1.4.0-3.el9_8
  • libkcapi-hmaccalc RHEL 9 1.4.0-3.el9_8
  • libkcapi hummingbird 1 1.5.1-0.1.hum1

red hat advisories RHSA-2026:69285RHSA-2026:67266RHSA-2026:67267RHSA-2026:67265RHSA-2026:56985

  • libkcapi AlmaLinux 9 1.4.0-3.el9_8
  • libkcapi-hmaccalc AlmaLinux 9 1.4.0-3.el9_8
  • libkcapi AlmaLinux 8 1.4.0-3.el8_10
  • libkcapi-hmaccalc AlmaLinux 8 1.4.0-3.el8_10
  • libkcapi AlmaLinux 10 1.5.1-1.el10_2
  • libkcapi-hasher AlmaLinux 10 1.5.1-1.el10_2
  • libkcapi-hmaccalc AlmaLinux 10 1.5.1-1.el10_2

almalinux advisories ALSA-2026:67265ALSA-2026:67266ALSA-2026:67267

  • libkcapi Rocky Linux 9 1.4.0-3.el9_8
  • libkcapi Rocky Linux 10 1.5.1-1.el10_2
  • libkcapi Rocky Linux 8 1.4.0-3.el8_10

rocky linux advisories RLSA-2026:67265RLSA-2026:67267RLSA-2026:67266

  • libkcapi Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 1.5.1-r0

alpine advisories ALPINE-CVE-2026-71227

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libkcapi Azure Linux 3.0 1.5.1-1

azure linux advisories AZL-94661

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-71227 updated cvss 5.1

libkcapi: Infinite loop denial of service in libkcapi _kcapi_aio_read_all() due to unhandled io_getevents() timeout return

  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux BaseOS (v. 8) libkcapi 1.4.0-3.el8_10, libkcapi-hmaccalc 1.4.0-3.el8_10
    fixed: vendor fix RHSA-2026:67266
  • Red Hat Enterprise Linux BaseOS (v. 9) libkcapi 1.4.0-3.el9_8, libkcapi-hmaccalc 1.4.0-3.el9_8
    fixed: vendor fix RHSA-2026:67265
  • Red Hat Enterprise Linux BaseOS (v. 10) libkcapi 1.5.1-1.el10_2, libkcapi-hasher 1.5.1-1.el10_2, libkcapi-hmaccalc 1.5.1-1.el10_2
    fixed: vendor fix RHSA-2026:67267
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) libkcapi 1.5.0-6.el10_0
    fixed: vendor fix RHSA-2026:69285
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) libkcapi 1.4.0-2.el9_6.1, libkcapi-hmaccalc 1.4.0-2.el9_6.1
    fixed: vendor fix RHSA-2026:87712
  • Red Hat Hardened Images libkcapi 1.5.1-0.1.hum1, libkcapi-tests 1.5.1-0.1.hum1, libkcapi-tools 1.5.1-0.1.hum1, libkcapi-hasher 1.5.1-0.1.hum1, libkcapi-hmaccalc 1.5.1-0.1.hum1, libkcapi-fipscheck 1.5.1-0.1.hum1
    fixed: vendor fix RHSA-2026:56985
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) libkcapi-hasher 1.5.0-6.el10_0, libkcapi-hmaccalc 1.5.0-6.el10_0 Red Hat Enterprise Linux BaseOS EUS (v.9.6) libkcapi-tests-debuginfo 1.4.0-2.el9_6.1, libkcapi-tools-debuginfo 1.4.0-2.el9_6.1, libkcapi-hmaccalc-debuginfo 1.4.0-2.el9_6.1, libkcapi-fipscheck-debuginfo 1.4.0-2.el9_6.1
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2462867 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.1 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.1 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Stephan Muelle libkcapi
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat OpenShift Container Platform 4
  • Red Hat Red Hat OpenShift Container Platform 5

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.