7.5

CVE-2020-36478: arm mbed_tls Improper Certificate Validation

CVSS: 7.5v3.1HighModified
AliasesUBUNTU-CVE-2020-36478DEBIAN-CVE-2020-36478
Published 23-08-2021Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2020-36478 is a high (CVSS 7.5) Improper Certificate Validation vulnerability in arm mbed_tls. EPSS estimates a 1.10% chance of exploitation in the next 30 days, higher than 65.2% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
40/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
1.10%
0%100%
Low · -0.08 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 2
DLA-2826-1DLA-3249-1

Timeline

  1. 23-08-2021
    PublishedVulnerability first disclosed.
  2. 04-08-2024
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

1.10%

Chance of exploitation in the next 30 days

Percentile

65%

Versus all other CVEs

30-day change

-0.08 pp

From 1.18% on 20-09-2026

20-09-202620-10-2026
EPSS score
1.10%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • githubUnverified

    Mbedtls

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Debian2 products
Siemens2 products
Arm1 product
  • mbed_tls< 2.7.18 | ≥ 2.8.0, < 2.16.9 | ≥ 2.17.0, < 2.25.0
Ubuntu1 product
  • mbedtlsAll versions (No fix recorded)

4 vendors · 6 products

References

10 links