Cyber Resilience

CVE-2020-36478

HighPublic PoC

Published: 23 August 2021

Published
23 August 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS Score 0.0052 67.2th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2020-36478 is a high-severity Improper Certificate Validation (CWE-295) vulnerability in Arm Mbed Tls. Its CVSS base score is 7.5 (High).

Operationally, ranked in the top 32.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

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…

more

the parameters do not match in any way, then the certificate should be considered invalid.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

arm
mbed tls
≤ 2.7.18 · 2.8.0 — 2.16.9 · 2.17.0 — 2.25.0
siemens
logo\! cmr2020 firmware
≤ 2.2
siemens
logo\! cmr2040 firmware
≤ 2.2
siemens
simatic rtu3031c firmware
all versions
siemens
simatic rtu3041c firmware
all versions
siemens
simatic rtu3030c firmware
all versions
siemens
simatic rtu3000c firmware
all versions
debian
debian linux
10.0, 9.0

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-295

When certificates are used to establish component provenance, the control requires correct certificate validation procedures.

addresses: CWE-295

Mandates approved trust anchors and issuance policies, directly preventing acceptance of unvalidated or untrusted certificates.

addresses: CWE-295

Correct system time is required for proper enforcement of certificate notBefore/notAfter dates and time-based revocation checks.

References