CVE-2025-47917

Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function mbedtls_x509_string_to_names() takes a head argument that is documented as an output argument. The documentation does not suggest that the function will free that pointer; however, the function does call mbedtls_asn1_free_named_data_list() on that argument, which performs a deep free(). As a result, application code that uses this function (relying only on documented behavior) is likely to still hold pointers to the memory blocks that were freed, resulting in a high risk of use-after-free or double-free. In particular, the two sample programs x509/cert_write and x509/cert_req are affected (use-after-free if the san string contains more than one DN).

Affected products

Debian, Linuxmint, Ubuntu, Mbed Tls

Arm Mbed Tls

< 3.6.4

Fix

Available

CVSS 3.1

9.8 CRITICAL

EPSS

2.0% (79th percentile)

Weakness

CWE-416

NVD status

Modified

Published

2025-07-20