Overview
The vulnerability identified as CVE-2025-52496 is a serious security flaw found in the Mbed TLS library before the release of version 3.6.4. This vulnerability, if exploited, can lead to a significant compromise of system security through the extraction of AES keys from multithreaded programs. This could potentially allow an attacker to perform a GCM forgery, leading to data leakage or even complete system compromise.
The reason why this vulnerability matters is due to the widespread use of the Mbed TLS library in numerous applications. Any application utilizing versions of this library prior to 3.6.4 is potentially at risk.
Vulnerability Summary
CVE ID: CVE-2025-52496
Severity: High (CVSS: 7.8)
Attack Vector: Local
Privileges Required: Low
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
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Product | Affected Versions
Mbed TLS | Before 3.6.4
How the Exploit Works
The exploit works by taking advantage of a race condition in the AESNI detection functionality of the Mbed TLS library. If certain compiler optimizations occur, an attacker can manipulate the concurrent execution of threads to trick the system into revealing the AES key. This key can then be used to decrypt sensitive data or perform a GCM forgery.
Conceptual Example Code
While the exact code will vary based on the specific implementation of the Mbed TLS library, a conceptual example may look something like this:
#include "mbedtls/aes.h"
int main() {
mbedtls_aes_context aes;
unsigned char key[16];
mbedtls_aes_init(&aes);
mbedtls_aes_setkey_enc(&aes, key, 128);
// At this point, due to the vulnerability,
// another thread could potentially extract the AES key
// from the aes context while it's being used for encryption.
// ... Rest of the code ...
return 0;
}Mitigation Guidance
The recommended mitigation for this vulnerability is to update the Mbed TLS library to version 3.6.4 or later, where the vulnerability has been patched. If this is not immediately feasible, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary mitigation. However, these are not permanent solutions and the library should be updated as soon as possible to fully secure your system.