PatchSiren cyber security CVE debrief

CVE-2026-34874 Trustedfirmware CVE debrief

CVE-2026-34874 is a HIGH severity vulnerability in Mbed TLS, a cryptographic library developed by Trustedfirmware. The vulnerability, discovered through [source-item], allows an attacker to write to address 0 via distinguished name parsing, potentially leading to a crash or other unspecified impact. The vulnerability has a CVSS score of 7.5 and is classified as CWE-476: NULL Pointer Dereference.

Vendor: Trustedfirmware
Product: Mbed TLS
CVSS: HIGH 7.5
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 versions 3.5.0 through 3.6.5 and 4.0.0 should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by a NULL pointer dereference in distinguished name parsing. This occurs when the library attempts to access a NULL pointer, leading to a potential crash or other unspecified impact.

Defensive priority

HIGH

Recommended defensive actions

Upgrade to Mbed TLS version 3.6.6 or later
Upgrade to Mbed TLS version 4.0.1 or later
Refer to [ref-4] and [ref-5] for vendor advisories and mitigation guidance

Evidence notes

Evidence for this CVE comes from [nvd] and [cve-org].

Sources and references

Verified primary and authoritative sources

CVE-2026-34874 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-34874

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-34874 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-34874

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

Supplemental references

Mitigation or vendor reference
Unverified legacy reference

URL: https://mbed-tls.readthedocs.io/en/latest/security-advisories/

[email protected] - Vendor Advisory
Mitigation or vendor reference
Unverified legacy reference

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

[email protected] - Vendor Advisory

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.