CVE-2025-9823 — mautic/core
CVE-2025-9823 is a Cross-site Scripting (XSS) vulnerability in mautic/core. A fix is available for mautic/core — see the affected versions and patch details below.
Reflected XSS in lead:addLeadTags - Quick Add
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-9823.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
mautic/core🐘mautic/core🐘mautic/coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
SummaryA 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.
DetailsThe 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.
ImpactA 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-in user.
References * Web Security Academy: Cross-site scripting https://portswigger.net/web-security/cross-site-scripting
- Web Security Academy: Reflected cross-site scripting https://portswigger.net/web-security/cross-site-scripting/reflected
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | mautic/core | ≥ 4.4.0&&< 4.4.17 | 4.4.17composer require mautic/core:^4.4.17 |
| 🐘Packagist | mautic/core | ≥ 5.0.0-alpha&&< 5.2.8 | 5.2.8composer require mautic/core:^5.2.8 |
| 🐘Packagist | mautic/core | ≥ 6.0.0-alpha&&< 6.0.5 | 6.0.5composer require mautic/core:^6.0.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mautic/core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mautic/core to 4.4.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-9823 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-9823 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-9823. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-9823 in your dependencies?
O3 Security finds CVE-2025-9823 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.