CVE-2021-41163

CRITICAL

Discourse - Remote Code Execution via Unvalidated subscribe_url

Title source: manual
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2021-41163. PoCs published by ibrahmsql.

AI-analyzed exploit summary This is a functional exploit PoC for CVE-2021-41163, targeting Discourse's theme import functionality to achieve remote code execution. The exploit crafts a malicious theme ZIP file with JavaScript, CSS, and template injection payloads, then uploads it via an authenticated admin session.

Description

Discourse is an open source platform for community discussion. In affected versions maliciously crafted requests could lead to remote code execution. This resulted from a lack of validation in subscribe_url values. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. To workaround the issue without updating, requests with a path starting /webhooks/aws path could be blocked at an upstream proxy.

Exploits (2)

nomisec WORKING POC 3 stars
by ibrahmsql · poc
https://github.com/ibrahmsql/CVE-2021-41163

This is a functional exploit PoC for CVE-2021-41163, targeting Discourse's theme import functionality to achieve remote code execution. The exploit crafts a malicious theme ZIP file with JavaScript, CSS, and template injection payloads, then uploads it via an authenticated admin session.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Discourse < 2.7.8, Discourse < 2.8.0.beta6
Auth required
Prerequisites: Authenticated admin access to Discourse · Network access to the target Discourse instance · Ability to upload theme files
devstral-2 · analyzed Feb 16, 2026 Full analysis →
nomisec WORKING POC 2 stars
by ibrahmsql · poc
https://github.com/ibrahmsql/discourse-CVE-2021-41163

This is a functional exploit PoC for CVE-2021-41163, targeting Discourse's theme import functionality to achieve remote code execution. It includes multiple payload types (JavaScript, CSS, Handlebars, etc.) and attempts privilege escalation if admin access is not initially available.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: Discourse < 2.7.8, Discourse < 2.8.0.beta6
Auth required
Prerequisites: Admin access or privilege escalation via bypass techniques · Network access to the Discourse instance
devstral-2 · analyzed Feb 16, 2026 Full analysis →

Scores

CVSS v3 10.0
EPSS 0.1981
EPSS Percentile 97.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Details

CWE
CWE-74
Status published
Products (2)
discourse/discourse 2.8.0 beta1 (6 CPE variants)
discourse/discourse < 2.7.9
Published Oct 20, 2021
Tracked Since Feb 18, 2026