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CVE-2026-74253 – Unauthenticated Remote Code Execution – Sourcerer extension for Joomla (versions 1.

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Summary

CVE-2026-74253 is a critical unauthenticated remote code execution vulnerability in the Sourcerer extension for Joomla, developed by Regular Labs. The flaw arises because Sourcerer executes {source} code blocks found anywhere in Joomla’s final rendered HTML output without verifying that the code originated from a trusted, privileged source. It carries the maximum CVSS score of 10.0 and requires no authentication or user interaction to exploit.

Technical details

  • Root cause: Sourcerer scans the fully rendered HTML output of a Joomla page for {source} tags and executes the CSS, JavaScript, or PHP code they contain, without reliably confirming that the tag was authored by a privileged/trusted user rather than injected via reflected input.
  • Trigger conditions: Any mechanism that causes attacker-controlled text containing a {source} tag to appear in the rendered page output (e.g., reflected parameters, user-submitted content, or other injection points) can cause Sourcerer to treat that text as legitimate code and execute it.
  • Attack vector: Network — no authentication and no user interaction are required (CVSS v4.0: AV:N/AC:L/AT:N/PR:N/UI:N).
  • Impact: Full compromise of confidentiality, integrity, and availability of the affected Joomla site, as PHP code injected via this mechanism can be executed server-side (CWE-94, Improper Control of Generation of Code; CAPEC-242, Code Injection).

Affected software

  • Sourcerer extension for Joomla (Regular Labs), versions 1.0.0 through 13.1.1

Severity

  • CVSS v4.0 Base Score: 10.0 (Critical)
  • Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Mitigation and recommended actions

  • Immediate: Upgrade Sourcerer to version 14.0.0 or later, which prevents reflected or otherwise unverified rendered Sourcerer code from executing by default while continuing to allow verified article and Custom module code.
  • If immediate patching is not possible: Restrict or temporarily disable the Sourcerer plugin/module until the update can be applied, and review site content and third-party integrations for any unexpected {source} tags that may indicate injected content.
  • Note that versions 13.0.0–13.1.1 introduced related hardening (restricting PHP execution to content from Super Users and enforcing configured CSS/JavaScript/PHP permissions), but these releases do not fully remediate CVE-2026-74253; only 14.0.0 addresses this specific issue.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Raw response body: /plugins/system/sourcerer/, /media/sourcerer/

References

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Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

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Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

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Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

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