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CVE-2026-34872

Arm Mbed Tls vulnerability

9.1 CRITICALEPSS 0.28%
  1. Published1 Apr 2026

Description

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).

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Arm Mbed Tls< 3.6.6
Arm Tf-psa-crypto1.0.0

Remediation

Fixed in
Arm Mbed Tls≥ 3.6.6

References

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Frequently asked

Is CVE-2026-34872 being actively exploited?

CVE-2026-34872 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.28%.

How severe is CVE-2026-34872?

CVE-2026-34872 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.28% probability of exploitation.

Which products are affected by CVE-2026-34872?

Affected products include Arm Mbed Tls, Arm Tf-psa-crypto.

How do I fix CVE-2026-34872?

Upgrade affected software to a fixed version, for example Arm Mbed Tls 3.6.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-34872 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.