5.9

CVE-2020-20949: ietf public_key_cryptography_standards_\#1

CVSS: 5.9v3.1MediumModified
Published 20-01-2021Last modified 09-07-2026
Open JSON

Vulnerability summary

CVE-2020-20949 is a medium (CVSS 5.9) vulnerability in ietf public_key_cryptography_standards_\#1. EPSS estimates a 0.94% chance of exploitation in the next 30 days, higher than 60.1% 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
0.94%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 20-01-2021
    PublishedVulnerability first disclosed.
  2. 09-07-2026
    Last modifiedVulnerability information updated.

Description

Bleichenbacher's attack on PKCS #1 v1.5 padding for RSA in STM32 cryptographic firmware library software expansion for STM32Cube (UM1924). The vulnerability can allow one to use Bleichenbacher's oracle attack to decrypt an encrypted ciphertext by making successive queries to the server using the vulnerable library, resulting in remote information disclosure.

CVSS metrics

2 scores · 1 source · 2 versions

EPSS trend

Probability

0.94%

Chance of exploitation in the next 30 days

Percentile

60%

Versus all other CVEs

30-day change

+0.01 pp

From 0.93% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.94%

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

St20 products
Ietf1 product

2 vendors · 21 products

References

3 links