CVE-2020-10932: Arm Mbed TLS

Medium severity, CVSS 4.7. EPSS: 0.3% chance of exploitation in the next 30 days.

An issue was discovered in Arm Mbed TLS before 2.16.6 and 2.7.x before 2.7.15. An attacker that can get precise enough side-channel measurements can recover the long-term ECDSA private key by (1) reconstructing the projective coordinate of the result of scalar multiplication by exploiting side channels in the conversion to affine coordinates; (2) using an attack described by Naccache, Smart, and Stern in 2003 to recover a few bits of the ephemeral scalar from those projective coordinates via several measurements; and (3) using a lattice attack to get from there to the long-term ECDSA private key used for the signatures. Typically an attacker would have sufficient access when attacking an SGX enclave and controlling the untrusted OS.

Affected products

• Arm Mbed TLS: from 2.7.0, before 2.7.15 (fixed in 2.7.15)
• Debian Debian Linux: version 10.0 only
• Fedoraproject Fedora: version 31 only; version 32 only
• Trustedfirmware Mbed TLS: from 2.16.0, before 2.16.6 (fixed in 2.16.6)

Published 2020-04-15. Last modified 2026-06-17.