Vulnerability · Published Aug 5, 2026 · Assigned by redhat
CVE-2026-71225Libkcapi: iv reuse in libkcapi one-shot symmetric cipher chunking causes cipher state reset across chunk boundaries
Medium 6.5
In plain English
A medium-severity weak randomness in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | libkcapi | 1.5.1-1.el10_2 | ALSA-2026:67267 |
| AlmaLinux:8 | libkcapi | 1.4.0-3.el8_10 | ALSA-2026:67266 |
| AlmaLinux:9 | libkcapi | 1.4.0-3.el9_8 | ALSA-2026:67265 |
| AlmaLinux:10 | libkcapi-hasher | 1.5.1-1.el10_2 | ALSA-2026:67267 |
| AlmaLinux:10 | libkcapi-hmaccalc | 1.5.1-1.el10_2 | ALSA-2026:67267 |
| AlmaLinux:8 | libkcapi-hmaccalc | 1.4.0-3.el8_10 | ALSA-2026:67266 |
| AlmaLinux:9 | libkcapi-hmaccalc | 1.4.0-3.el9_8 | ALSA-2026:67265 |
| Alpine:v3.21 | libkcapi | 1.5.1-r0 | ALPINE-CVE-2026-71225 |
| Alpine:v3.22 | libkcapi | 1.5.1-r0 | ALPINE-CVE-2026-71225 |
| Alpine:v3.23 | libkcapi | 1.5.1-r0 | ALPINE-CVE-2026-71225 |
| Alpine:v3.24 | libkcapi | 1.5.1-r0 | ALPINE-CVE-2026-71225 |
| Debian:12 | libkcapi | no fix listed | DEBIAN-CVE-2026-71225 |
| Debian:13 | libkcapi | no fix listed | DEBIAN-CVE-2026-71225 |
| Debian:14 | libkcapi | 1.5.1-1 | DEBIAN-CVE-2026-71225 |
| Rocky Linux:10 | libkcapi | 0:1.5.1-1.el10_2 | RLSA-2026:67267 |
| Rocky Linux:8 | libkcapi | 0:1.4.0-3.el8_10 | RLSA-2026:67266 |
| Rocky Linux:9 | libkcapi | 0:1.4.0-3.el9_8 | RLSA-2026:67265 |
| Ubuntu:22.04:LTS | libkcapi | no fix listed | UBUNTU-CVE-2026-71225 |
| Ubuntu:24.04:LTS | libkcapi | no fix listed | UBUNTU-CVE-2026-71225 |
| Ubuntu:26.04:LTS | libkcapi | no fix listed | UBUNTU-CVE-2026-71225 |
| Ubuntu:26.10 | libkcapi | no fix listed | UBUNTU-CVE-2026-71225 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Stephan Muelle | libkcapi | 0.10.1 – before 1.5.1 |
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | see references |
| Red Hat | Red Hat Hardened Images | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 5 | see references |
Weakness: CWE-330 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
References
- RHSA-2026:56985 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:67265 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:67266 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:67267 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:69285 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:87712 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-71225 vdb-entry, x_refsource_REDHAT
- RHBZ#2462011 issue-tracking, x_refsource_REDHAT