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Vulnerability record · CVE-2025-47917 · published 20 July 2025

CVE-2025-47917: Arm mbed tls use after free vulnerability

Arm · Mbed Tls

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).

9.8 CVSS 3.1 Critical EPSS 2.1% · top 18.7% CWE-416 · Use after free
9.8CVSS 3.1 base score
2.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-7.md MitigationThird 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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-47917), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.