CVE-2016-6887 Matrixssl CVE debrief

Who should care

Organizations that embed or distribute MatrixSSL, especially products using RSA-based cryptography in network-facing services. This is most relevant for firmware teams, OEMs, appliance vendors, and security engineers responsible for crypto library upgrades and release validation.

Technical summary

The supplied NVD data describes a flaw in MatrixSSL's pstm_exptmod modular exponentiation routine. Because the operation is not performed correctly, an attacker may be able to leverage a Chinese Remainder Theorem (CRT) attack to infer a secret key. NVD classifies the weakness as CWE-200 and rates the issue CVSS 3.0 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N, indicating remote reachability with high confidentiality impact but no listed integrity or availability impact.

Defensive priority

Medium overall, but higher priority for any exposed or long-lived MatrixSSL deployment. The bug affects cryptographic key handling, so remediation should be scheduled promptly for systems that process untrusted network traffic or rely on RSA key operations.

Recommended defensive actions

• Inventory all products and firmware using MatrixSSL and confirm whether the deployed version is 3.8.6 or earlier.
• Upgrade to a MatrixSSL release that includes the vendor fix; use the MatrixSSL advisory referenced in the NVD record to confirm the corrected version.
• If immediate upgrade is not possible, reduce exposure by limiting network access to affected services and prioritizing replacement of affected crypto components.
• Validate after upgrade that TLS/crypto functionality still works as expected, including certificate handling and key exchange paths.
• Track the affected product line for any vendor-specific backports or firmware updates that include the MatrixSSL fix.

Evidence notes

The debrief is based only on the supplied NVD record and referenced vendor/third-party links. The record states that MatrixSSL 3.8.6 and earlier are vulnerable, that pstm_exptmod does not properly perform modular exponentiation, and that a remote attacker might predict the secret key via a CRT attack. NVD lists CVSS 3.0 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N and CWE-200. No CISA KEV metadata was supplied. Timing context uses the provided CVE publishedAt of 2017-01-13T16:59:00.277Z; later modified timestamps are not treated as the issue date.

Official resources