7.5

CVE-2021-36369: debian debian_linux Improper Authentication

Modified
AliasesMGASA-2022-0436UBUNTU-CVE-2021-36369DEBIAN-CVE-2021-36369
Published 12-10-2022Last modified 15-05-2025

Vulnerability summary

CVE-2021-36369 is a high (CVSS 7.5) Improper Authentication vulnerability in debian debian_linux. EPSS estimates a 1.86% chance of exploitation in the next 30 days, higher than 79.3% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 2% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
1.86%
0%100%
Low · +0.37 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
USN-7292-1

Timeline

  1. 12-10-2022
    PublishedVulnerability first disclosed.
  2. 15-05-2025
    Last modifiedVulnerability information updated.

Description

An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

1.86%

Chance of exploitation in the next 30 days

Percentile

79%

Versus all other CVEs

30-day change

Increase +0.37 pp

From 1.49% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Debian2 products
  • dropbear< 2018.76-5+deb10u2 | < 2022.82-1
  • debian_linuxEOL10.0
Dropbear_ssh_project1 product
Mageia1 product
  • dropbear< 2020.81-1.1.mga8
Ubuntu1 product
  • dropbearAll versions (No fix recorded) | < 2017.75-3ubuntu0.1~esm1 | < 2019.78-2ubuntu0.1~esm1 | < 2020.81-5ubuntu0.1

4 vendors · 5 products

References

10 links