What’s Vulnerable › Vulnerabilities

CVE-2026-34874

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-01 · updated 2026-06-17
• Weakness: CWE-476

Description

An issue was discovered in Mbed TLS through 3.6.5 and 4.x through 4.0.0. There is a NULL pointer dereference in distinguished name parsing that allows an attacker to write to address 0.

Affected products

• TrustedFirmware Mbed TLS: from 3.5.0 before 3.6.6; 4.0.0 — fixed in 3.6.6

How to fix

Upgrade to a fixed version: TrustedFirmware Mbed TLS 3.6.6. Check the vendor advisory for mitigations.

References

• https://mbed-tls.readthedocs.io/en/latest/security-advisories/
• https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-null-pointer-dereference-x509/

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