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

CVE-2026-35482 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/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 before version 2.0-M5-2606 allows administrators to execute arbitrary commands on servers hosting the platform, enabling complete server compromise and potential data theft or service…

How to fix or mitigate CVE-2026-35482?

Within 24 hours: Inventory all alf.io deployments across your infrastructure and document current versions and administrator account assignments. Immediately implement strict access controls limiting administrative console access to named, trusted users only and enable audit logging of all administrative actions. Within 7 days: Deploy multi-factor authentication (MFA) for all alf.io administrative accounts and conduct a privilege audit to remove unnecessary administrator rights; additionally, review server firewall rules to restrict access to alf.io administrative interfaces to authorized networks only. Within 30 days: Monitor vendor communications and security channels for availability of version 2.0-M5-2606 or later; establish a patch deployment timeline and test the upgrade in a staging environment, prioritizing deployment as soon as a patch becomes available.

alf.io CVE-2026-35482

CRITICAL

Incorrect Authorization (CWE-863)

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

Authentication Bypass Java Alf

9.1

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.1 CRITICAL

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

vuln.today AI

9.1 CRITICAL

Network-reachable admin panel (AV:N) with reliable reflection technique (AC:L) but requires admin (PR:H); sandbox-to-host escape is a scope change (S:C) yielding full RCE (C/I/A:H).

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

4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Updated

Aug 12, 2026 - 18:14 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Aug 12, 2026 - 18:07 vuln.today

cvss_changed

Severity Changed

Aug 12, 2026 - 18:07 NVD

HIGH CRITICAL

CVSS changed

Aug 12, 2026 - 18:07 NVD

8.0 (HIGH) 9.1 (CRITICAL)

Analysis Generated

Jun 02, 2026 - 23:30 vuln.today

DescriptionNVD

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

Authenticated OS command execution in alf.io before version 2.0-M5-2606 lets a logged-in administrator escape the Rhino JavaScript sandbox that runs extension scripts and execute arbitrary commands on the underlying server. The break-out relies on an unguarded injected Java object (returnClass) plus an incomplete AST blocklist that together permit Java reflection without tripping any validation. Publicly available exploit context exists (SSVC exploitation: poc) but the flaw is not in CISA KEV and its EPSS score is very low (0.04%), consistent with a high-impact but privilege-gated issue.

Technical ContextAI

alf.io is an open-source event/ticket reservation platform. Its extension subsystem is designed to run operator-supplied JavaScript inside a restricted Mozilla Rhino sandbox so that customization logic cannot reach the host. The vulnerability arises because a Java object exposed to the script context (returnClass) is not guarded, and the abstract-syntax-tree (AST) blocklist meant to forbid dangerous language constructs is incomplete; the combination lets script code pivot through Java reflection to reach arbitrary classes and methods, fully defeating the sandbox without raising validation errors. This maps to CWE-863 (Incorrect Authorization): the sandbox's allow/deny enforcement is present but flawed, so an action that should be denied is authorized. The single affected product per CPE is cpe:2.3:a:alf:alf:*:*:*:*:*:*:*:*.

RemediationAI

Vendor-released patch: upgrade to alf.io 2.0-M5-2606, which closes the reflection path by guarding the returnClass object and tightening the extension AST blocklist; see GHSA-3w8f-mcf6-cm7h (https://github.com/alfio-event/alf.io/security/advisories/GHSA-3w8f-mcf6-cm7h). If you cannot upgrade immediately, reduce the attack surface by restricting the administrator role to the minimum set of trusted operators and rotating any shared admin credentials, since exploitation requires admin access; place the admin interface behind a VPN or IP allowlist rather than exposing it to the internet (trade-off: complicates remote administration); and if the extension/scripting feature is not used, disable or avoid granting the ability to create or edit extension scripts (trade-off: loses customization capability). These are compensating controls only - they narrow who can reach the flaw but do not remove it, so patching remains the real fix.