Side-channel exposure via ignored DRBG selection
Published Sep 5, 2024 · Updated Mar 14, 2025
Algorithm-selection failure in Mbed TLS since 2.26.0 allows local users to target the PSA subsystem's weaker side-channel resistance. The MBEDTLS_PSA_HMAC_DRBG_MD_TYPE option is documented as selecting HMAC_DRBG, but the PSA initialization path ignores it and selects CTR_DRBG whenever MBEDTLS_CTR_DRBG_C is enabled. Exposure requires that compile-time combination and a platform where software AES leaks useful timing or power information; random output quality remains cryptographically acceptable.
Summary
What happened
Algorithm-selection failure in Mbed TLS since 2.26.0 allows local users to target the PSA subsystem's weaker side-channel resistance. The MBEDTLS_PSA_HMAC_DRBG_MD_TYPE option is documented as selecting HMAC_DRBG, but the PSA initialization path ignores it and selects CTR_DRBG whenever MBEDTLS_CTR_DRBG_C is enabled. Exposure requires that compile-time combination and a platform where software AES leaks useful timing or power information; random output quality remains cryptographically acceptable.
The record
- CVE
- CVE-2024-45157
- Published
- Sep 5, 2024
- Updated
- Mar 14, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-696
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 5, 2024CVE publishedPublication date reported by the CVE source.
- Mar 14, 2025Record updatedLatest update available in the CVE record.
Exploitability
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