What is the CVSS score of CVE-2026-35482?

CVE-2026-35482 has a CVSS 3.1 base score of 8.0 (High). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of alf.io are affected by CVE-2026-35482?

alf.io ticket reservation system contains a critical sandbox escape vulnerability (CVE-2026-35482) that allows authenticated administrators to execute arbitrary operating system commands on the host…

How to fix or mitigate CVE-2026-35482?

Within 24 hours: Audit administrative account access logs in all alf.io deployments and restrict admin access to essential personnel only. Within 7 days: Upgrade all alf.io instances to version 2.0-M5-2606 or later. Within 30 days: Implement multi-factor authentication for administrative accounts, review system command execution logs for unauthorized activity, and establish ongoing monitoring for suspicious administrator actions.

alf.io CVE-2026-35482

HIGH

Incorrect Authorization (CWE-863)

2026-06-02 security-advisories@github.com

Java Authentication Bypass

8.0

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

8.0 HIGH

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

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

High

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Jun 02, 2026 - 23:30 vuln.today

DescriptionGitHub Advisory

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.

AnalysisAI

Sandbox escape in alf.io ticket reservation system prior to version 2.0-M5-2606 allows an authenticated administrator to break out of the Rhino JavaScript extension engine and execute arbitrary OS commands on the host. The flaw stems from an unguarded injected returnClass Java object combined with an incomplete AST blocklist, enabling reflection-based escape without triggering validation. No public exploit identified at time of analysis, but the vendor advisory (GHSA-3w8f-mcf6-cm7h) confirms the issue and a patched release is available.

Technical ContextAI

alf.io is an open-source conference and event ticketing platform written in Java. Its extension subsystem embeds the Mozilla Rhino JavaScript engine to let administrators script custom event logic in a restricted sandbox. To enforce safety, alf.io combines two layers: an AST-based blocklist that statically rejects dangerous JavaScript constructs, and runtime restrictions on which Java classes the script can reach. The vulnerability - classified as CWE-863 (Incorrect Authorization) - arises because the returnClass host object is injected into the script scope without access guards, and the AST blocklist fails to enumerate every reflective access path. Together they allow an attacker-controlled script to pivot through java.lang.Class/java.lang.reflect APIs and obtain arbitrary class loading and method invocation, which in a Rhino-on-JVM context yields full host-level code execution. No CPE strings were provided in the input, so exact build identifiers must be derived from the GHSA advisory.

Affected ProductsAI

alf.io open-source ticket reservation platform, all versions prior to 2.0-M5-2606, is affected on any deployment that exposes the extension scripting feature to administrators. No CPE was supplied in the intelligence feed, so version identification relies on the upstream GitHub Security Advisory at https://github.com/alfio-event/alf.io/security/advisories/GHSA-3w8f-mcf6-cm7h. Downstream distributions, container images, and managed alf.io hosts built from pre-2.0-M5-2606 sources should be considered vulnerable until rebuilt against the patched release.

RemediationAI

Vendor-released patch: 2.0-M5-2606 - upgrade alf.io to this version or later, which closes both the unguarded returnClass injection and the AST blocklist gap, as described in the advisory at https://github.com/alfio-event/alf.io/security/advisories/GHSA-3w8f-mcf6-cm7h. If immediate upgrade is not possible, restrict the administrator role to the smallest possible set of trusted operators, disable or remove any custom extension scripts and prohibit creation of new ones via the admin UI (trade-off: loss of extensibility for event-specific automation), and place the alf.io admin interface behind a VPN, IP allowlist, or SSO with MFA to reduce the chance that admin credentials can be abused remotely. Audit existing extension scripts for use of returnClass, java.lang.Class, java.lang.reflect, or other reflective patterns before re-enabling, and rotate any secrets accessible to the JVM process, since a successful exploit on an unpatched host implies full OS-level compromise.