Security Advisory


· Please read carefully and check if the version of your Zammad system is affected by this vulnerability. Please send us information regarding vulnerabilities in Zammad!

Security Advisory Details

  • ID: ZAA-2021-06
  • Date: 06/08/2020
  • Title: Stored XSS in User Avatar
  • Severity: high
  • Product: Zammad 1.0.x up to 4.0.0
  • Fixed in: Zammad 4.0.1, 4.1.0
  • References:
    --> CVE: CVE-2021-35303

Vulnerability Descriptions

Stored XSS in User Avatar

Zammad comes with a functionality to allow Users to upload their own Avatars. The Avatar then gets converted into a displayable text value. It was possible for an attacker to store malicious code in that User Avatar attribute. Every time the Avatar will be shown the malicious code will be executed in the session of the current user.

Special 🙏 and 🤘 and ❤️ to:

  • N: ChungPD

This vulnerability is fixed in the latest versions of Zammad and it is recommended to upgrade to one of these.

Fixed releases can be found at:

Additional information

Online version of this advisory:

Send all remarks to security issues to

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