CVE-2021-27911: XSS vulnerability on contacts view

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-30 · updated 2026-06-17
Weakness: CWE-79

Description

Mautic versions before 3.3.4/4.0.0 are vulnerable to an inline JS XSS attack through the contact's first or last name and triggered when viewing a contact's details page then clicking on the action drop down and hovering over the Campaigns button. Contact first and last name can be populated from different sources such as UI, API, 3rd party syncing, forms, etc.

Affected products

Mautic: before 3.3.4; 4.0.0-alpha1, 4.0.0-beta, 4.0.0-rc — fixed in 3.3.4

How to fix

Upgrade to a fixed version: Mautic 3.3.4. Check the vendor advisory for mitigations.

References

https://github.com/mautic/mautic/security/advisories/GHSA-72hm-fx78-xwhc
https://github.com/mautic/mautic/security/advisories/GHSA-72hm-fx78-xwhc

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