# CVE-2026-35482: alf.io sandbox escape in extension script engine

Source: https://junglewise.ai/threats/cve-2026-35482-alf-io-sandbox-escape-in-extension-script-engine  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-02. Updated: 2026-06-02  
License: CC BY 4.0 with a link back

CVE-2026-35482 · Severity: high · CVSS 8 · Published 2026-06-02

alf.io is an open-source ticket reservation system used for managing events like conferences and workshops. A security flaw in the system's extension engine allows an administrator to bypass security restrictions and execute unauthorized commands on the underlying server. This could lead to a complete takeover of the server, resulting in the theft of attendee data, service outages, or the use of the server for further attacks.

Technologies: [Alf.Io](https://junglewise.ai/threats/technologies/alf-io). Vendors: [Alf.Io](https://junglewise.ai/threats/vendors/alf-io).

## Quick answers

**Is CVE-2026-35482 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-35482 being exploited in the wild.

**How severe is CVE-2026-35482?** High severity, with a CVSS score of 8, published 2 June 2026.

**Which products and versions are affected?** Alf.Io < 2.0-M5-2606.

**Is there a fix for CVE-2026-35482?** A patch was published on 2026-06-02. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-35482 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-35482?** Check whether you run Alf.Io at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A sandbox escape exists in the alf.io extension script engine due to the improper exposure of Java objects within the Rhino JavaScript environment. Specifically, the `ScriptingExecutionService.executeScriptFinally()` method injects an unrestricted `java.lang.Class` object (named `returnClass`) into the script scope. While the system attempts to use AST validation and a class whitelist to restrict script capabilities, an attacker can use `returnClass.forName()` and Java reflection to bypass these controls. By reflecting into `java.lang.Runtime`, an authenticated administrator can execute arbitrary OS commands. The vulnerability is triggered when a malicious extension script is saved and subsequently executed by a system event. This issue is patched in version 2.0-M5-2606.

## Affected products

- alfio-event alf.io < 2.0-M5-2606

## Timeline

- 2026-06-02: disclosed
- 2026-06-02: advisory
- 2026-06-02: patched

## References

- [https://github.com/alfio-event/alf.io/security/advisories/GHSA-3w8f-mcf6-cm7h](https://github.com/alfio-event/alf.io/security/advisories/GHSA-3w8f-mcf6-cm7h)

## Related threats

- [alf.io improper access control in configuration endpoints](https://junglewise.ai/threats/cve-2026-50165-alf-io-improper-access-control-in-configuration-endpoints)
- [Alf.io arbitrary file read and exfiltration in extension sandbox](https://junglewise.ai/threats/cve-2026-41412-alf-io-arbitrary-file-read-and-exfiltration-in-extension-sandbox)