#VU124805 Improper input validation in mbed TLS - CVE-2026-34872
Published: April 2, 2026
Vulnerability identifier: #VU124805
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-34872
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
mbed TLS
mbed TLS
Software vendor:
ARM
ARM
Description
The vulnerability allows a remote attacker to force the FFDH shared secret into a small set of values.
The vulnerability exists due to improper input validation in the FFDH key agreement component when processing a peer's public key during key agreement using PSA_ALG_FFDH. A remote attacker can send a specially crafted public key to force the FFDH shared secret into a small set of values.
Applications are only affected if they use the PSA API to perform FFDH as part of a larger protocol that expects contributory behaviour from FFDH. TLS 1.2 and TLS 1.3 are not affected due to protocol-level protections.
Remediation
Install security update from vendor's website.