Input validation error in TF-PSA-Crypto and mbed TLS - CVE-2026-54434
Published: July 13, 2026
Vulnerability identifier: #VU137396
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-54434
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: ARM
Affected software:
TF-PSA-Crypto
mbed TLS
TF-PSA-Crypto
mbed TLS
Detailed vulnerability description
The vulnerability allows a remote attacker to force the ECDH shared secret to a fixed value.
The vulnerability exists due to improper input validation in the built-in Curve25519 (X25519) ECDH implementation when performing key agreement with PSA_ALG_ECDH. A remote attacker can supply input that results in an all-zero shared secret to force the ECDH shared secret to a fixed value.
Only builds with MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED are vulnerable, and the issue applies to protocols that require contributory behaviour.
How to mitigate CVE-2026-54434
Install security update from vendor's website.