CVE-2024-45159: mbed tls Cert Validation Flaw — Fix

Description

An issue was discovered in Mbed TLS 3.x before 3.6.1. With TLS 1.3, when a server enables optional authentication of the client, if the client-provided certificate does not have appropriate values in if keyUsage or extKeyUsage extensions, then the return value of mbedtls_ssl_get_verify_result() would incorrectly have the MBEDTLS_X509_BADCERT_KEY_USAGE and MBEDTLS_X509_BADCERT_KEY_USAGE bits clear. As a result, an attacker that had a certificate valid for uses other than TLS client authentication would nonetheless be able to use it for TLS client authentication. Only TLS 1.3 servers were affected, and only with optional authentication (with required authentication, the handshake would be aborted with a fatal alert).

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CVSS v3.1 Score

9.8

CRITICAL

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

Weakness Type (CWE)

CWE-295 CWE-295

Affected Products

Vendor	Product	Versions
arm	mbed_tls	3.2.0 — 3.6.1

References

Advisories & Patches

https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2024-08-3/

Other References

https://github.com/Mbed-TLS/mbedtls/releases/ https://mbed-tls.readthedocs.io/en/latest/security-advisories/

Frequently Asked Questions

What is CVE-2024-45159? +

An issue was discovered in Mbed TLS 3.x before 3.6.1. With TLS 1.3, when a server enables optional authentication of the client, if the client-provided certificate does not have appropriate values in if keyUsage or extKeyUsage extensions, then the return value of mbedtls_ssl_get_verify_result() would incorrectly have the MBEDTLS_X509_BADCERT_KEY_USAGE and MBEDTLS_X509_BADCERT_KEY_USAGE bits clear. As a result, an attacker that had a certificate valid for uses other than TLS client authentication would nonetheless be able to use it for TLS client authentication. Only TLS 1.3 servers were affected, and only with optional authentication (with required authentication, the handshake would be aborted with a fatal alert). It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2024-45159? +

CVE-2024-45159 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2024-45159? +

CVE-2024-45159 affects products from arm, specifically: mbed_tls. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-45159? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2024-45159