9.1

CVE-2021-21809: moodle OS Command Injection

CVSS: 9.1v3.1CriticalModified
AliasesUBUNTU-CVE-2021-21809
Published 23-06-2021Last modified 03-08-2024
Open JSON

Vulnerability summary

CVE-2021-21809 is a critical (CVSS 9.1) OS Command Injection vulnerability in moodle. EPSS estimates a 24.17% chance of exploitation in the next 30 days, higher than 97.8% of scored vulnerabilities. 3 public exploits are recorded.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.1/10
010
Critical · v3.1 (NVD)
EPSS score
24.17%
0%100%
High · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits3reference, metasploit

Timeline

  1. 23-06-2021
    PublishedVulnerability first disclosed.
  2. 03-08-2024
    Last modifiedVulnerability information updated.

Description

A command execution vulnerability exists in the default legacy spellchecker plugin in Moodle 3.10. A specially crafted series of HTTP requests can lead to command execution. An attacker must have administrator privileges to exploit this vulnerabilities.

CVSS metrics

6 scores · 3 sources · 3 versions

EPSS trend

Probability

24.17%

Chance of exploitation in the next 30 days

Percentile

98%

Versus all other CVEs

30-day change

0.00 pp

From 24.17% on 20-09-2026

20-09-202620-10-2026
EPSS score
24.17%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

3 found
  • referenceUnverified

    Exploit Reference (talosintelligence.com)

    Maturity: unknown

  • referenceUnverified

    Exploit Reference (packetstormsecurity.com)

    Maturity: unknown

  • MetasploitMetasploitremoteVerified

    Moodle SpellChecker Path Authenticated Remote Command Execution

    exploit/multi/http/moodle_spelling_path_rce

    Maturity: weaponized

Weaknesses

CWE · root cause

Affected systems

Moodle1 product
Ubuntu1 product
  • moodleAll versions (No fix recorded)

2 vendors · 2 products

References

4 links