Use After Free Affecting mbedtls package, versions <3.6.4-r0


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

Exploit Maturity
Proof of Concept
EPSS
1.99% (79th percentile)

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  • Snyk IDSNYK-ALPINE320-MBEDTLS-10876055
  • published22 Jul 2025
  • disclosed20 Jul 2025

Introduced: 20 Jul 2025

CVE-2025-47917  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Alpine:3.20 mbedtls to version 3.6.4-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream mbedtls package and not the mbedtls package as distributed by Alpine. See How to fix? for Alpine:3.20 relevant fixed versions and status.

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 Base Scores

version 3.1