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CVE-2026-34872

Status: AnalyzedCritical (9.1)—

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

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

Vulnerabilidad en FFDH sin validación de entrada (CWE-347) en librerías criptográficas accesibles por red; atacante remoto puede manipular el secreto compartido. La falta de comportamiento contributivo permite ataque de intermediario, impactando autenticación (T1553) y derivación de claves (T1187).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Privileged Account ManagementFilter Network TrafficVulnerability ScanningRestrict Registry PermissionsPassword PoliciesOperating System Configuration

Affected technologies (2)

ARM — Mbed TLSARM — Tf-psa-crypto

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-34872",
  "cveTags": [],
  "metrics": {
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          "options": [
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          "version": "2.0.3",
          "timestamp": "2026-04-01T19:51:10.004400Z"
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  "published": "2026-04-01T20:16:27.493",
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      "url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/",
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    {
      "url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-ffdh-peerkey-checks/",
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    }
  ],
  "lastModified": "2026-06-17T10:39:46.057",
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