CVE-2026-42796: Arelle < 2.39.10 Unauthenticated RCE via /rest/configure

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 18 Sep 2026. It cites 9 public reports, the first from 18 Sep 2026.

• dashboard.shadowserver.org
• dashboard.shadowserver.org
• dashboard.shadowserver.org

How likely is exploitation in the next 30 days?

2.7%

Down from 3.9% on 23 Oct 2026.

EPSS score, percentile 86.2 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

9.2 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• before 2.39.10

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 30 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

Arelle < 2.39.10 Unauthenticated RCE via /rest/configure

Arelle before 2.39.10 contains an unauthenticated remote code execution vulnerability in the /rest/configure REST endpoint that accepts a plugins query parameter and forwards it to the plugin manager without authentication or authorization. Attackers can supply a URL to a malicious Python file through the plugins parameter, causing the Arelle webserver to download and execute the attacker-controlled code within the Arelle process with its privileges.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

• github.com (Release notes, Patch)

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline