CVE-2026-71225

Libkcapi, the user-space library that exposes the Linux kernel crypto API, improperly reuses the same initialization vector (IV) for every internal 64 KiB data chunk when a one-shot symmetric cipher operation is performed on inputs larger than 64 KiB in stateful modes such as Counter (CTR) or Cipher Block Chaining (CBC). A remote attacker can trigger the flaw by causing an application that uses libkcapi to process specially crafted large inputs. Repeated IV use in these modes exposes relationships in the encrypted plaintext, so the attacker gains degraded confidentiality of the processed data and possibly incorrect cryptographic processing affecting integrity, though not code execution. Affected parties are users of the upstream smuellerdd libkcapi project and Red Hat distributions and images that ship it (Red Hat Enterprise Linux, Red Hat hardened images, and OpenShift Container Platform), limited to deployments where applications actually link and call the library. No exploitation in the wild is known; the issue is documented in a public Red Hat Bugzilla reference, and EPSS currently assigns a 0.3% probability of exploitation in the next 30 days.

What to do: Upgrade libkcapi to the fixed release published by the upstream project or via Red Hat advisories covering Red Hat Enterprise Linux, hardened images, and OpenShift, and track Red Hat Bugzilla #2462011 (https://bugzilla.redhat.com/show_bug.cgi?id=2462011) for fix details. As an interim mitigation, have applications avoid one-shot symmetric operations on inputs larger than 64 KiB in CTR or CBC, instead processing data in smaller chunks with freshly initialized IVs. Inventory which deployed systems and applications link against libkcapi to confirm actual exposure, since the flaw only matters for code paths that call the library.