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).
This page covers CVE-2025-47917 as tracked by Ubuntu, for the package mbedtls. No fixed version has been recorded for this distribution yet.
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
UBUNTU-CVE-2025-47917 is classified as CWE-416: Use After Free. Memory is used after being released, so its contents may already belong to something else.
UBUNTU-CVE-2025-47917 is recorded against 1 package.
Published on 20 July 2025 and last revised on 22 April 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
ubuntu.com (Report)
www.cve.org (Report)
github.com (Report)
ubuntu.com (Advisory)
mbedtls has other advisories on record. If you are patching this one, these are worth checking on the same host:
These advisories are the same class of weakness (CWE-416: Use After Free) in other software:
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| mbedtls | — | — |
References
Similar Threats
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