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vulnerability / NVI-00006250 / Revision 4

Mautic vulnerable to reflected XSS in lead:addLeadTags - Quick Add

OSV carries this publisher advisory for mautic/core, mautic/core, mautic/core. This is an aggregated source copy; consult the original publisher and compare update dates.

source listedactiveGHSA-9v8p-m85m-f7mmCVE-2025-9823

This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.

01 / Meaning

Why it matters

Published affected context helps an owner decide what evidence to gather. This report has not examined your application.

EPSS

0.317%

FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.2469. Missing scores are unknown.

As of · FIRST EPSS

02 / Applicability

The affected context

Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.

mautic/core

source listed
  • ECOSYSTEM: introduced 4.4.0; fixed 4.4.17

## Summary A Cross-Site Scripting (XSS) vulnerability allows an attacker to execute arbitrary JavaScript in the context of another user’s session. This occurs because user-supplied input is reflected back in the server’s response without proper sanitization or escaping, potentially enabling malicious actions such as session hijacking, credential theft, or unauthorized actions in the application. ## Details The vulnerability resides in the “Tags” input field on the /s/ajax?action=lead:addLeadTags endpoint. Although the server applies sanitization before storing the data or returning it later, the payload is executed immediately in the victim’s browser upon reflection, allowing an attacker to run arbitrary JavaScript in the user’s session. ## Impact A Reflected XSS attack can have a significant impact, allowing attackers to steal sensitive user data like cookies, redirect users to malicious websites, manipulate the web page content, and essentially take control of a user's session within an application by executing malicious JavaScript code within the victim's browser, even if the server-side code is secure; essentially enabling them to perform actions as if they were the logged-

GitHub Advisory Database via OSV

mautic/core

source listed
  • ECOSYSTEM: introduced 5.0.0-alpha; fixed 5.2.8

## Summary A Cross-Site Scripting (XSS) vulnerability allows an attacker to execute arbitrary JavaScript in the context of another user’s session. This occurs because user-supplied input is reflected back in the server’s response without proper sanitization or escaping, potentially enabling malicious actions such as session hijacking, credential theft, or unauthorized actions in the application. ## Details The vulnerability resides in the “Tags” input field on the /s/ajax?action=lead:addLeadTags endpoint. Although the server applies sanitization before storing the data or returning it later, the payload is executed immediately in the victim’s browser upon reflection, allowing an attacker to run arbitrary JavaScript in the user’s session. ## Impact A Reflected XSS attack can have a significant impact, allowing attackers to steal sensitive user data like cookies, redirect users to malicious websites, manipulate the web page content, and essentially take control of a user's session within an application by executing malicious JavaScript code within the victim's browser, even if the server-side code is secure; essentially enabling them to perform actions as if they were the logged-

GitHub Advisory Database via OSV

mautic/core

source listed
  • ECOSYSTEM: introduced 6.0.0-alpha; fixed 6.0.5

## Summary A Cross-Site Scripting (XSS) vulnerability allows an attacker to execute arbitrary JavaScript in the context of another user’s session. This occurs because user-supplied input is reflected back in the server’s response without proper sanitization or escaping, potentially enabling malicious actions such as session hijacking, credential theft, or unauthorized actions in the application. ## Details The vulnerability resides in the “Tags” input field on the /s/ajax?action=lead:addLeadTags endpoint. Although the server applies sanitization before storing the data or returning it later, the payload is executed immediately in the victim’s browser upon reflection, allowing an attacker to run arbitrary JavaScript in the user’s session. ## Impact A Reflected XSS attack can have a significant impact, allowing attackers to steal sensitive user data like cookies, redirect users to malicious websites, manipulate the web page content, and essentially take control of a user's session within an application by executing malicious JavaScript code within the victim's browser, even if the server-side code is secure; essentially enabling them to perform actions as if they were the logged-

GitHub Advisory Database via OSV

03 / Response

What to do next

  1. vendor patch

    The original advisory lists fixed boundaries 4.4.17 for mautic/core. Confirm the publisher’s latest guidance.

    Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV

  2. vendor patch

    The original advisory lists fixed boundaries 5.2.8 for mautic/core. Confirm the publisher’s latest guidance.

    Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV

  3. vendor patch

    The original advisory lists fixed boundaries 6.0.5 for mautic/core. Confirm the publisher’s latest guidance.

    Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV

  4. investigate

    Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.

    Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS

A fixed release is not deployment evidence.

Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.

04 / Limits

What this report cannot establish

  • Customer inventory, deployment, reachability and exploitation have not been inspected.
  • NVD lastModified does not establish freshness of every associated CPE record.
Read the collection and interpretation limits ↗

05 / Provenance

Sources you can inspect

Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.

  1. GHSA-9v8p-m85m-f7mm ↗

    GitHub Advisory Database via OSV · vendor advisory

    Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.

  2. CVE-2025-9823 ↗

    NIST National Vulnerability Database · official catalog

    Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.

  3. CVE-2025-9823 ↗

    FIRST EPSS · official catalog

    Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.

Public revision history

Only published revisions appear here. Routine fetches do not create a material-change event.

  1. Revision 4 ·

    Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.

  2. Revision 3 ·

    Source facts changed; compare the preserved prior revision.

  3. Revision 2 ·

    Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.

  4. Revision 1 ·

    First indexed by Null; source disclosure date is shown separately.

Read the public revision data ↗

The next step is private

Bring the question into your environment.

The connected workflow is a development preview for inventory, contextual matching, owner decisions and evidence-based verification. No system-specific result is generated by this page.

See the synthetic workflow preview ↗