CVE intelligence

CVE-2026-34872

Vulnerability intelligence

Published Apr 1, 2026Sources checked Nov 13, 2026

9.1CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-34872 and is rated Critical severity with a CVSS score of 9.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Nov 12, 2026

Release Notes

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-34872?

An issue was discovered in Mbed TLS 3.5.x and 3.6.x through 3.6.5 and TF-PSA-Crypto 1.0. There is a lack of contributory behavior in FFDH due to improper input validation.

Using finite-field Diffie-Hellman, the other party can force the shared secret into a small set of values (lack of contributory behavior). This is a problem for protocols that depend on contributory behavior (which is not the case for TLS).

The attack can be carried by the peer, or depending on the protocol by an active network attacker (person in the middle).

Source: NVD