medium · CVSS 6.5

CVE-2026-71225

Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundaries

Published 5 Aug 2026 · Source updated 2 Nov 2026 · Retrieved 2026-11-04 15:50 UTC · This record may be stale; verify the source

Statance checks for CVE-2026-71225. Connected servers are checked automatically against the fixed versions their distribution or package ecosystem has published for it, including app dependency lockfiles. Check my servers ↗

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What happened?

A flaw was found in libkcapi. When performing one-shot symmetric cipher operations on large inputs (over 64 KiB) in stateful modes such as Counter (CTR) or Cipher Block Chaining (CBC), the library improperly reuses the Initialization Vector (IV) for each internal data chunk. A remote attacker could potentially exploit this by making an application that uses libkcapi process specially crafted large inputs. This can lead to a significant weakening of data confidentiality, as the repeated IV use can expose relationships in encrypted plaintext, and may also affect data integrity by causing incorrect cryptographic processing.

Description supplied by CVE Program. Formatting is simplified; follow the original advisory for full details.

Affected software and versions

Source-provided software and version information
Software	Version information	Fixed version
libkcapiStephan Muelle	affected: 0.10.1 to < 1.5.1	See vendor advisory
libkcapiRed Hat	unaffected: 0:1.5.1-1.el10_2 to < *	See vendor advisory
libkcapiRed Hat	unaffected: 0:1.5.0-6.el10_0 to < *	See vendor advisory
libkcapiRed Hat	unaffected: 0:1.4.0-3.el8_10 to < *	See vendor advisory
libkcapiRed Hat	unaffected: 0:1.4.0-3.el9_8 to < *	See vendor advisory
libkcapiRed Hat	unaffected: 0:1.4.0-2.el9_6.1 to < *	See vendor advisory
libkcapi-mainRed Hat	unaffected: 1.5.1-0.1.hum1 to < *	See vendor advisory
openshift/ose-rhel-coreos-8Red Hat	Default status: affected	See vendor advisory
openshift/ose-rhel-coreos-9Red Hat	Default status: affected	See vendor advisory
openshift/ose-rhel-coreos-9Red Hat	Default status: affected	See vendor advisory

Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.

Is it being exploited?

This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.

CISA data retrieved 2026-11-06 16:38 UTC. Check CISA ↗

How to respond

Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.

Sources and remediation references

This public advisory does not determine whether a particular server is affected. Records are refreshed as sources change; verify urgent decisions against the original advisory.

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