# CVE-2026-21444: libtpms returns wrong initialization vector when certain symmetric ciphers are used

CVE-2026-21444 is fixed in 4 products on 1 platform, first by FEDORA-2026-21A2A74849, released January 2, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-21444
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0008
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 2, 2026
- Weakness: Use of a Broken or Risky Cryptographic Algorithm
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21444

## Description

libtpms, a library that provides software emulation of a Trusted Platform Module, has a flaw in versions 0.10.0 and 0.10.1. The commonly used integration of libtpms with OpenSSL 3.x contained a vulnerability related to the returned IV (initialization vector) when certain symmetric ciphers were used. Instead of returning the last IV it returned the initial IV to the caller, thus weakening the subsequent encryption and decryption steps. The highest threat from this vulnerability is to data confidentiality. Version 0.10.2 fixes the issue. No known workarounds are available.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libtpms Debian 14 | 0.10.2-1 | [DEBIAN-CVE-2026-21444](https://patchblox.com/security/data/fix/linux/debian-cve-2026-21444.md) | Jan 2, 2026 |
| Linux | libtpms Fedora 43 | 0.10.2-1.fc43 | [FEDORA-2026-21A2A74849](https://patchblox.com/security/data/fix/linux/fedora-2026-21a2a74849.md) | Jan 2, 2026 |
| Linux | libtpms-debuginfo Fedora 43 | 0.10.2-1.fc43 | [FEDORA-2026-21A2A74849](https://patchblox.com/security/data/fix/linux/fedora-2026-21a2a74849.md) | Jan 2, 2026 |
| Linux | libtpms-debugsource Fedora 43 | 0.10.2-1.fc43 | [FEDORA-2026-21A2A74849](https://patchblox.com/security/data/fix/linux/fedora-2026-21a2a74849.md) | Jan 2, 2026 |
| Linux | libtpms-devel Fedora 43 | 0.10.2-1.fc43 | [FEDORA-2026-21A2A74849](https://patchblox.com/security/data/fix/linux/fedora-2026-21a2a74849.md) | Jan 2, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.