Bug 2453966 (CVE-2026-34872) - CVE-2026-34872 mbedtls: Mbed TLS and TF-PSA-Crypto: Shared secret manipulation via improper FFDH input validation
Summary: CVE-2026-34872 mbedtls: Mbed TLS and TF-PSA-Crypto: Shared secret manipulatio...
Keywords:
Status: NEW
Alias: CVE-2026-34872
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2454195 2454198 2454200 2454204 2454208
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-01 20:01 UTC by OSIDB Bzimport
Modified: 2026-04-02 05:55 UTC (History)
0 users

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Description OSIDB Bzimport 2026-04-01 20:01:49 UTC 
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).
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