Vulnerability in Arm Mbed TLS
CVE-2026-34871
An issue was discovered in Mbed TLS before 3.6.6 and 4.x before 4.1.0 and TF-PSA-Crypto before 1.1.0. There is a Predictable Seed in a Pseudo-Random Number Generator (PRNG).
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.7 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (3.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 3.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000
Affected products
Weakness classification (CWE)
References
- mbed-tls.readthedocs.io/en/latest/security-advisories/ (Vendor Advisory)
- mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory… (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-34871?
- CVE-2026-34871 is a medium-severity vulnerability in Arm Mbed TLS, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 6.7/10. Published 2026-04-01.
- How severe is CVE-2026-34871?
- Medium severity. CVSS v3 base score is 6.7 out of 10.