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).

Overview

Severity
High (CVSS 8.9)
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:H
Exploit Status
Not Exploited
Patch Tuesday
2025-Jul
Released
2026-09-03
EPSS Score
2.06% (percentile: 80.1%)

Detection & Weaponization (1 sources)

Maturity: Exploit

  • GitHub PoC: 1 repositories

Affected Products (1)

Other

  • 21780-17084

Security Updates (1)

Revision History

  • 2026-09-03: Information published.