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    CVE-2021-36647

    Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.

    Published:Jan 17, 2023
    Last Modified:Jun 5, 2026
    EPS:Jan 17, 2023
    EPSS Score:0.0005
    CVSS Score:4.7

    Affected Products

    Vendor
    Arm
    Product
    Mbed Tls
    Vendor
    Trustedfirmware
    Product
    Mbed Tls

    Exploits

    No exploit reference

    Related CVEs

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    CVE-2026-34872 (CVSS 9.1) — An issue was discovered in Mbed TLS 3.5.x and 3.6.x through 3.6.5 and TF-PSA-Crypto 1.0. There is a lack of co…
    CVE-2026-34871 (CVSS 6.7) — An issue was discovered in Mbed TLS before 3.6.6 and 4.x before 4.1.0 and TF-PSA-Crypto before 1.1.0. There is…
    CVE-2025-66442 (CVSS 5.1) — In Mbed TLS through 4.0.0, there is a compiler-induced timing side channel (in RSA and CBC/ECB decryption) tha…
    CVE-2026-25835 (CVSS 7.7) — Mbed TLS before 3.6.6 and TF-PSA-Crypto before 1.1.0 misuse seeds in a Pseudo-Random Number Generator (PRNG).…
    CVE-2025-59438 (CVSS 5.3) — Mbed TLS through 3.6.4 has an Observable Timing Discrepancy.…
    CVE-2025-54764 (CVSS 6.2) — Mbed TLS before 3.6.5 allows a local timing attack against certain RSA operations, and direct calls to mbedtls…
    CVE-2025-48965 (CVSS 4) — Mbed TLS before 3.6.4 has a NULL pointer dereference because mbedtls_asn1_store_named_data can trigger conflic…
    CVE-2025-47917 (CVSS 8.9) — Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in acco…
    CVE-2025-52496 (CVSS 7.8) — Mbed TLS before 3.6.4 has a race condition in AESNI detection if certain compiler optimizations occur. An atta…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High