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    CVE-2020-36478

    An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.

    Published:Aug 23, 2021
    Last Modified:Nov 21, 2024
    EPS:Aug 23, 2021
    EPSS Score:0.00254
    CVSS Score:7.5

    Affected Products

    Vendor
    Arm
    Product
    Mbed Tls
    Vendor
    Debian
    Product
    Debian Linux
    Vendor
    Siemens
    Product
    Logo\! Cmr2020
    Vendor
    Siemens
    Product
    Logo\! Cmr2020 Firmware
    Vendor
    Siemens
    Product
    Logo\! Cmr2040
    Vendor
    Siemens
    Product
    Logo\! Cmr2040 Firmware
    Vendor
    Siemens
    Product
    Simatic Rtu3000c
    Vendor
    Siemens
    Product
    Simatic Rtu3000c Firmware
    Vendor
    Siemens
    Product
    Simatic Rtu3030c
    Vendor
    Siemens
    Product
    Simatic Rtu3030c Firmware
    Vendor
    Siemens
    Product
    Simatic Rtu3031c
    Vendor
    Siemens
    Product
    Simatic Rtu3031c Firmware
    Vendor
    Siemens
    Product
    Simatic Rtu3041c
    Vendor
    Siemens
    Product
    Simatic Rtu3041c Firmware

    Exploits

    https://github.com/ARMmbed/mbedtls/issues/3629https://github.com/ARMmbed/mbedtls/issues/3629

    Common Weakness Enumeration

    CWE-295 Improper Certificate Validation

    Related CVEs

    CVE-2026-34877 (CVSS 9.8) — An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection …
    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…

    References

    https://cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf
    https://github.com/ARMmbed/mbedtls/issues/3629
    https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.9
    https://github.com/ARMmbed/mbedtls/releases/tag/v2.25.0
    https://github.com/ARMmbed/mbedtls/releases/tag/v2.7.18
    https://lists.debian.org/debian-lts-announce/2021/11/msg00021.html
    https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html
    https://cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf
    https://github.com/ARMmbed/mbedtls/issues/3629
    https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.9
    https://github.com/ARMmbed/mbedtls/releases/tag/v2.25.0
    https://github.com/ARMmbed/mbedtls/releases/tag/v2.7.18
    https://lists.debian.org/debian-lts-announce/2021/11/msg00021.html
    https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html

    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