CVE-2025-13828: Mautic flaw lets low‑privilege users install packages — why businesses must act now

Mautic’s composer slip-up lets low‑privilege users install code — CVE‑2025‑13828 puts marketing stacks at risk

What happened (quick recap)

CVE‑2025‑13828 is a high‑impact vulnerability discovered in Mautic where a non‑privileged user can install and remove arbitrary Composer packages on Composer‑based installations. Crucially, the issue allows this even if the application setting labelled “enable composer based update” is unticked. The documented impact is straightforward: a low‑privilege account can introduce malicious code via Composer and use that code to obtain higher privileges. The vulnerability has been scored at 9.0 (Critical).

Who is affected and why this matters to businesses

If you run Mautic — whether self‑hosted for marketing automation, as part of an agency stack, or as a subsystem inside a larger application — you should consider yourself directly affected until you can confirm otherwise. That includes third parties and suppliers who host or manage Mautic instances on your behalf.

This is not just a marketer’s problem. Composer is the PHP ecosystem’s package manager, and allowing arbitrary package installation from a web‑accessible interface is, bluntly, a supply‑chain and privilege management failure. A malicious package can drop a web shell, escalate privileges, exfiltrate customer data, or pivot into other systems on your network. For organisations that treat marketing systems as perimeter‑soft rather than core, this is a painful reminder that any internet‑facing application is a potential route to your crown jewels.

What could happen if similar vulnerabilities are ignored

Ignore this at your peril. Practical consequences of the flaw (or a successful exploit) include:

• Privilege escalation: a lowly account turns into an admin or code‑execution vector.

• Remote code execution and persistence: malicious Composer packages can drop backdoors or scheduled tasks.

• Data theft and regulatory exposure: contact lists, campaign data and PII can be accessed and leaked — GDPR and customer trust are at stake.

• Supply‑chain compromise: attackers can introduce malicious dependencies that affect other applications when shared or reused.

How this links to recognised standards and good practice

This incident neatly illustrates why ISO 27001 is not an academic exercise. Relevant ISO 27001 control areas include:

• Access control (A.9) — ensure accounts have the minimum rights required and regularly review role assignments.

• Operations security (A.12) — harden application deployment, restrict execution of uploaded/installed artefacts, and monitor operational logs for unusual package installs.

• System acquisition, development and maintenance (A.14) — secure the software supply chain, validate third‑party packages, and apply secure development lifecycle practices.

• Information security incident management (A.16) — be prepared to detect, contain and recover from a compromise.

For business continuity, ISO 22301 reminds us that an incident affecting a customer‑facing service such as Mautic can disrupt operations, damage reputation, and cause loss of revenue. Planning for continuity and rapid recovery reduces business impact; see Synergos’ ISO 22301 resource for more on structuring those arrangements.

If you want a formal route to close gaps raised by this class of vulnerability, Synergos’ ISO 27001 service page is a good place to start for pragmatic alignment with these controls.

Immediate mitigations you should apply right now

Until you have a definitive vendor patch or advisory, take these practical steps. They are deliberately prioritized for speed and effectiveness:

• Check admin accounts and roles — remove unused or test accounts and ensure least privilege is enforced. Require MFA for all administrative or privileged logins.

• Restrict access to the Mautic admin interface — limit by IP, VPN or network ACLs where possible.

• Harden the web host: remove or restrict Composer binaries from web‑accessible directories, tighten file‑system permissions, and prevent execution from upload or media folders (e.g. using web server config, open_basedir, disable_functions).

• Inventory and lock dependencies — pin Composer packages, use a private package proxy or allow‑list known sources, and run software composition analysis (SCA) to spot suspicious packages.

• Deploy WAF rules to look for unusual package‑management API calls and monitor logs for composer create, install or remove actions initiated by non‑privileged accounts.

• Review backups and recovery plans — ensure backups are isolated and tested so you can recover if code is tampered with (tie this work into your ISO 22301 plans).

Longer‑term fixes and control maturity

Addressing the technical vector is necessary but not sufficient. Adopt a layered approach that includes supplier and development controls:

• Secure development and deployment pipelines: do not allow production package installs from a UI; require CI/CD‑driven deployments with code review gates.

• Supply‑chain governance: vet third‑party packages, use signed packages where possible, and run dependency scanning as part of your release process.

• Operational monitoring and threat hunting: create alerts for anomalous package management activity and implement a playbook for rapid containment.

These measures map back to ISO 27001 controls and to good vendor governance — if you use external agencies to manage marketing platforms, ensure contracts and SLAs require secure configuration and incident notification.

How Synergos can help (without sounding like a hard sell)

Fixing the technical risk is straightforward for a competent ops or dev team, but embedding the right controls across people, process and technology is where most organisations struggle. Synergos offers pragmatic support that ties security fixes into ISO 27001‑aligned management systems and business continuity planning under ISO 22301.

If you need immediate help: tightening access controls, reviewing roles, and hardening the hosting environment are quick wins that Synergos consultants can support. For longer term resilience, Synergos also provides security awareness training and Cyber Essentials alignment to raise the baseline hygiene of staff and systems.

Useful Synergos links: ISO 27001 — https://synergosconsultancy.co.uk/iso27001/; ISO 22301 — https://synergosconsultancy.co.uk/iso-22301-business-continuity-management-system-bcms/; security awareness training — https://synergosconsultancy.co.uk/usecure; Cyber Essentials — https://synergosconsultancy.co.uk/iasme-certifications/.

Final thoughts — act before someone else writes your post‑mortem

In short, CVE‑2025‑13828 is a textbook example of how convenience features and insufficiently enforced configuration can become an attack vector. Treat composer access and package management like a supply‑chain control: lock it down, monitor it, and bake it into your ISO 27001 controls and business continuity plans. Patching and technical fixes are critical, but putting the controls, governance and testing in place is what prevents the same mistake from recurring.

Think of it this way: letting an unprivileged account install packages is a bit like leaving a ladder propped against the vault door and handing out invitations to climb it. Don’t be that organisation.