What is CVE-2021-43393?

CVE-2021-43393 is a medium-severity vulnerability in St J-Safe3, classified under Improper Verification of Cryptographic Signature. CVSS score: 6.2/10. Published 2022-03-04.

How severe is CVE-2021-43393?

Medium severity. CVSS v3 base score is 6.2 out of 10.

Vulnerability in St J-Safe3

CVE-2021-43393

STMicroelectronics STSAFE-J 1.1.4, J-SAFE3 1.2.5, and J-SIGN sometimes allow attackers to abuse signature verification. This is associated with the ECDSA signature algorithm on the Java Card J-SAFE3 and STSAFE-J platforms exposing a 3.0.4 Java Card API. It is exploitable for STSAFE-J in closed configuration and J-SIGN (when signature verification is activated) but not for J-SAFE3 EPASS BAC and EAC products. It might also impact other products based on the J-SAFE-3 Java Card platform.

Published 2022-03-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.002 (3.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 3.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

St J-Safe3
St J-Safe3 Firmware — versions 1.2.5
St Stsafe-J
St Stsafe-J Firmware — versions 1.1.4

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

community.st.com/s/toparticles (Vendor Advisory)
www.cert.ssi.gouv.fr/avis/CERTFR-2022-AVI-169/ (Third Party Advisory)

Frequently asked questions

What is CVE-2021-43393?: CVE-2021-43393 is a medium-severity vulnerability in St J-Safe3, classified under Improper Verification of Cryptographic Signature. CVSS score: 6.2/10. Published 2022-03-04.
How severe is CVE-2021-43393?: Medium severity. CVSS v3 base score is 6.2 out of 10.