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AlfApplication

CVE-2026-35482

CRITICAL · 9.1 CVSS v3.1 Published 2026-06-02
Fix available
A fix is available. Upgrade to 2.0-M5-2606 or later.
See remediation →
97/100
Remediation priority · Urgent
Public exploit Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
alf.io is an open source ticket reservation system for conferences, trade shows, workshops, and meetups. Prior to version 2.0-M5-2606, a sandbox escape vulnerability in the alf.io extension script engine allows an authenticated administrator to execute arbitrary operating system commands on the server. The extension system is intended to execute restricted JavaScript in a sandboxed Rhino environment; however, a combination of an unguarded injected Java object (`returnClass`) and an incomplete AST blocklist allows the sandbox to be fully escaped using Java reflection without triggering any validation errors. Version 2.0-M5-2606 patches the issue.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A sandbox escape vulnerability in alf.io's extension script engine allows authenticated administrators to execute arbitrary OS commands. The extension system uses a sandboxed Rhino JavaScript environment, but an unguarded injected Java object (returnClass) combined with an incomplete AST blocklist permits Java reflection to escape the sandbox completely without triggering validation errors.

MitigationUpgrade to version 2.0-M5-2606 or later. Until then, restrict administrative access to trusted users only and consider disabling the extension script engine if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AlfApplication
Affected:< 2.0-M5-2606

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm alf.io installation
    Locate the alf.io application - check for web application artifacts, Java WAR/JAR files, or the application running on its default ports (typically 8080). Look for alf.io-specific directories or files in the deployment environment.
    Affected if alf.io is present and running in the environment
  2. Identify installed version
    Check the alf.io version - examine the JAR/WAR file name, look in the admin dashboard under 'About' or 'System Information', or review startup logs for the version string. Compare against 2.0-M5-2606.
    Affected if Version is before 2.0-M5-2606 (e.g., 2.0-M5-2605, earlier releases, or any version missing the '-2606' suffix in the M5 milestone)
  3. Verify extension script engine access
    Log into the alf.io admin interface and navigate to the 'Extensions' or 'Script Engine' section. Confirm whether the Rhino JavaScript sandbox feature is available and accessible to administrator accounts.
    Affected if The extension/script engine feature is enabled and accessible to admin users
  4. Confirm admin account existence
    Review the alf.io user management panel to verify at least one administrator account exists. The vulnerability requires authenticated admin privileges to exploit.
    Affected if Any administrator account is present and active in the system

The environment is affected if alf.io is installed with a version prior to 2.0-M5-2606 and the extension script engine feature is accessible to an authenticated administrator.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.0-M5-2606 or later
Fixed in 2.0-M5-2606
Interim mitigation

Upgrade to version 2.0-M5-2606 or later. Until then, restrict administrative access to trusted users only and consider disabling the extension script engine if not required.

Recommended fix Moderate confidence

2.0-M5-2606

  1. Upgrade alf.io to version 2.0-M5-2606 or later to receive the security patch for the sandbox escape vulnerability.
  2. If immediate upgrade is not possible, consider restricting administrator access to trusted personnel only, as this exploit requires an authenticated administrator account.
  3. Review extension script configurations and monitor for any suspicious JavaScript execution patterns.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Alf Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-35482 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data