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Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVE-2021-27131

Medium
5.4/10

Summary

Moodle is vulnerable to persistent/stored cross-site scripting (XSS) due to the improper input sanitization on the "Additional HTML Section" via "Header and Footer" parameter in /admin/settings.php. This vulnerability is leading an attacker to steal admin and all user account cookies by storing the malicious XSS payload in Header and Footer. NOTE: this is disputed by the vendor because the "Additional HTML Section" for "Header and Footer" can only be supplied by an administrator, who is intentionally allowed to enter unsanitized input (e.g., site-specific JavaScript).

  • LOW
  • NETWORK
  • LOW
  • CHANGED
  • REQUIRED
  • LOW
  • LOW
  • NONE

CWE-79 - Cross Site Scripting

Cross-Site Scripting, commonly referred to as XSS, is the most dominant class of vulnerabilities. It allows an attacker to inject malicious code into a pregnable web application and victimize its users. The exploitation of such a weakness can cause severe issues such as account takeover, and sensitive data exfiltration. Because of the prevalence of XSS vulnerabilities and their high rate of exploitation, it has remained in the OWASP top 10 vulnerabilities for years.

References

Advisory Timeline

  • Published