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Fencer Vulns
high 8.0

CVE-2026-35482 json

alf.io has an Authenticated RCE via Extension Script Sandbox Escape

published 2026-06-02 5 mo ago modified 2026-08-12 2 mo ago also EUVD-2026-34050

cvss
8.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits
0
none known

Summary

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.

Patch / fix

  • alf alf 2.0-M5-2606

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
5 mo ago

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/alfio-event/alf.io/security/advisories/GHSA-3w8f-mcf6-cm7h referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected products

  • alfio-event alf.io

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.