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PatchSiren cyber security CVE debrief

CVE-2026-34871 Arm CVE debrief

CVE-2026-34871 is a MEDIUM severity vulnerability in Mbed TLS and TF-PSA-Crypto, with a CVSS score of 6.7. 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).

Vendor
Arm
Product
Mbed TLS
CVSS
MEDIUM 6.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-01
Original CVE updated
2026-06-05
Advisory published
2026-04-01
Advisory updated
2026-06-05

Who should care

Users of Mbed TLS before 3.6.6 and 4.x before 4.1.0 and TF-PSA-Crypto before 1.1.0 should be aware of this vulnerability.

Technical summary

The vulnerability is caused by a predictable seed in a Pseudo-Random Number Generator (PRNG) in Mbed TLS and TF-PSA-Crypto.

Defensive priority

MEDIUM

Recommended defensive actions

  • Upgrade Mbed TLS to version 3.6.6 or later, or 4.1.0 or later.
  • Upgrade TF-PSA-Crypto to version 1.1.0 or later.
  • Refer to [ref-4](https://mbed-tls.readthedocs.io/en/latest/security-advisories/) and [ref-5](https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-dev-random/) for vendor advis

Evidence notes

The vulnerability was published on 2026-04-01 and modified on 2026-06-05.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-34871 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-34871

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-34871 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-34871

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.