5.9

CVE-2020-36477: arm mbed_tls Improper Certificate Validation

CVSS: 5.9v3.1MediumModified
AliasesUBUNTU-CVE-2020-36477DEBIAN-CVE-2020-36477
Published 23-08-2021Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2020-36477 is a medium (CVSS 5.9) Improper Certificate Validation vulnerability in arm mbed_tls. EPSS estimates a 0.86% chance of exploitation in the next 30 days, higher than 57.9% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
5.9/10
010
Medium · v3.1 (NVD)
EPSS score
0.86%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

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 2.24.0. The verification of X.509 certificates when matching the expected common name (the cn argument of mbedtls_x509_crt_verify) with the actual certificate name is mishandled: when the subjecAltName extension is present, the expected name is compared to any name in that extension regardless of its type. This means that an attacker could impersonate a 4-byte or 16-byte domain by getting a certificate for the corresponding IPv4 or IPv6 address (this would require the attacker to control that IP address, though).

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.86%

Chance of exploitation in the next 30 days

Percentile

58%

Versus all other CVEs

30-day change

0.00 pp

From 0.86% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.86%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Arm1 product
Debian1 product
  • mbedtls< 2.28.0-0.3
Ubuntu1 product
  • mbedtlsAll versions (No fix recorded)

3 vendors · 3 products

References

6 links