CVE-2025-48965

What it actually does

NULL pointer dereference triggered in mbedtls_asn1_store_named_data when ASN.1 named data storage receives a val.p of NULL paired with a non-zero val.len value, causing invalid memory access during parsing of certificate or configuration data.

Why it matters to the business

Applications relying on Mbed TLS for secure communications may experience unexpected crashes, leading to denial of service, interrupted TLS handshakes, and degraded availability of encrypted services without data exposure.

How an attack unfolds

An attacker supplies specially crafted ASN.1 structures containing conflicting named data fields during certificate processing or configuration loading; the library stores the data without validating the pointer-length pair, resulting in a NULL dereference crash on access.

How to fix it

Upgrade armmbed/mbedtls to the commit c765c831e5c2a0971410692f92f7a81d6ec65ec2 or later equivalent release; rebuild and redeploy all dependent applications after verification.

How to confirm the fix worked

Confirm the installed library version or commit hash matches or exceeds the fixed commit; perform regression testing with ASN.1 inputs containing NULL pointer and non-zero length combinations to ensure no crash occurs.

Typical attack path

1. Identify a target application or service that uses vulnerable Mbed TLS for ASN.1 or certificate handling
2. Craft and deliver ASN.1 input with val.p NULL and val.len greater than zero via network protocol, file, or API call
3. Trigger processing of the malformed data in mbedtls_asn1_store_named_data
4. Cause NULL pointer dereference leading to process crash or denial of service

How to detect it

Inspect application and system logs for segmentation faults or crashes occurring during certificate parsing or ASN.1 processing; correlate with inbound connections or configuration loads involving Mbed TLS.

What your security team should do

• Prioritize upgrade of Mbed TLS across all products to the fixed commit within standard patch windows given low exploit maturity
• Monitor upstream releases and rebuild pipelines for the affected GIT repository
• Review ASN.1 parsing code paths for similar validation gaps in custom integrations