Vulnerability Description
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).
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Arm | Mbed Tls | < 3.6.4 |
Related Weaknesses (CWE)
References
- https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-sMitigationThird Party Advisory
- https://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories/Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/08/msg00013.html
- https://lists.debian.org/debian-lts-announce/2025/08/msg00025.html
FAQ
What is CVE-2025-47917?
CVE-2025-47917 is a vulnerability with a CVSS score of 8.9 (HIGH). 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 ar...
How severe is CVE-2025-47917?
CVE-2025-47917 has been rated HIGH with a CVSS base score of 8.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-47917?
Check the references section above for vendor advisories and patch information. Affected products include: Arm Mbed Tls.