CVE-2026-62203

Executive Summary

CVE-2026-62203 is an environment variable filtering vulnerability in OpenClaw versions prior to 2026.6.6. The flaw exists within the host execution functionality, where improper sanitization of rustup startup variables allows attackers with lower-trust caller access or configured input paths to execute or persist actions beyond their intended authorization level. Successful exploitation could lead to complete compromise of confidentiality, integrity, and availability, given the severe CVSS base score of 8.8, and affects any deployment running vulnerable OpenClaw versions with untrusted caller inputs.

Technical Analysis

Vulnerability Class and Mechanism

This vulnerability falls under CWE-184 — Incomplete List of Disallowed Inputs. The core weakness is that OpenClaw maintains a filtering mechanism for environment variables during host execution, but this filter operates on an incomplete denylist. Specifically, the rustup startup variables are not included in the sanitization routine, allowing them to pass through unfiltered.

Rustup Context: Rustup is the official toolchain installer for the Rust programming language. It relies on environment variables such as those controlling toolchain overrides, proxy settings, and network configuration. When rustup initializes its environment, it reads a set of startup variables from the environment. If an attacker can inject or manipulate these variables, they can alter rustup's behavior — potentially redirecting toolchain resolution, loading malicious dynamic libraries, or executing arbitrary commands during the startup sequence.

Injection Vector: The attack surface is the host exec functionality that invokes external commands. When OpenClaw's host exec path executes a rustup-related binary or a command that triggers rustup initialization, the environment variable filter is supposed to strip dangerous variables. Due to the incomplete denylist (CWE-184), rustup-specific variables bypass this filter. Attackers who can influence the execution environment — via lower-trust caller access or configured input paths that feed data into the environment — can inject malicious values into these variables.

Authorization Bypass: The flaw is not merely about environment pollution. The NVD description explicitly notes that exploitation allows attackers to "execute or persist actions beyond their intended authorization level." This suggests the injected environment variables influence privilege boundary checks or command execution paths, causing OpenClaw to execute commands with higher privileges than the caller is entitled to. The persistence element indicates that the injection can survive across sessions or reboots, potentially via environment modifications that affect subsequent excutions.

Attack Surface Details: Insufficient technical detail is provided regarding the exact function names, code paths, or specific rustup variable names. The vulnerability is reachable through two primary vectors: (1) lower-trust callers who can invoke host exec with crafted inputs, and (2) configured input paths that OpenClaw processes, where the content can influence environment variable values.

Exploitation Scenarios

Note: No public PoC, Nuclei template, or exploit code is available for this CVE. The attack chain below is inferred from the vulnerability class and NVD description.

Step 1: Reconnaissance and Target Identification

An attacker first identifies an OpenClaw instance running a version prior to 2026.6.6. This can be achieved through:

• Banner grabbing on services exposed via network (the CVSS vector indicates network adjacency: AV:N).
• Identifying OpenClaw-specific API endpoints or management interfaces.
• Enumerating the software version through error messages, response headers, or feature-specific behaviors.

The attacker must establish an authenticated session with low-privilege access (PR:L), as the CVSS vector indicates a requirement for low privileges. This could come from a standard user account, a tenant with restricted permissions, or a lower-trust automation caller.

Step 2: Triggering the Flaw

The attacker identifies a host exec endpoint or configured input path that allows them to influence the environment passed to rustup-related operations. The attack requires:

1. A legitimate invocation path that executes rustup or triggers rustup initialization.
2. An injection point where the attacker can insert or modify environment variables — either directly through parameter injection in the host exec request, or indirectly through content written to configured input paths that are later processed.

Because the filter relies on an incomplete denylist, rustup startup variables are not inspected or stripped. The attacker crafts a request that sets malicious values for these variables.

Step 3: Payload and Execution

At the vulnerability-class level, the attacker injects environment variables that will be consumed by rustup during its startup sequence. Potential payloads include:

• Setting variables that override rustup toolchain paths to point to attacker-controlled locations.
• Injecting proxy variables to redirect network-dependent rustup operations to attacker-controlled servers.
• Setting dynamic linker or library path variables that cause rustup to load malicious shared objects during initialization.

The precise mechanism by which environment variable injection escalates to authorization bypass is not documented in available sources. However, the NVD description confirms that the resulting execution occurs "beyond their intended authorization level," indicating the injected variables disrupt privilege checks or cause execution within a higher-trust context.

Step 4: Post-Exploitation Impact

Successful exploitation yields three critical impacts per the CVSS vector:

• Confidentiality (C:H): The attacker can read sensitive data, credentials, or configuration files accessible to the higher-privilege execution context.
• Integrity (I:H): The attacker can modify system files, plant persistence mechanisms, or alter application behavior.
• Availability (A:H): The attacker can disrupt operations, deny service to legitimate users, or corrupt critical data.

The "persist actions" language in the NVD description suggests the attacker can establish persistent access, potentially by modifying startup scripts, adding cron jobs, or planting malicious toolchain components that survive system restarts. No threat actor campaigns or in-the-wild exploitation evidence is available at the time of reporting.

Impact Assessment

CVSS Score: 8.8 (High) — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

• Attack Vector: Network — The vulnerability is exploitable remotely.
• Attack Complexity: Low — No special conditions needed beyond access to the vulnerable function.
• Privileges Required: Low — The attacker needs only low-privilege access, making this accessible to a broad range of users including unprivileged accounts.
• User Interaction: None — No victim action is required for exploitation.
• Scope: Unchanged — The vulnerability affects only the OpenClaw environment, not the broader infrastructure.

Business Impact: OpenClaw deployments are typically used for automation, orchestration, and multi-tenant task execution. A successful exploit could cause:

• Data Breach: Exfiltration of sensitive data processed by the OpenClaw instance, including credentials, business data, and API keys.
• System Takeover: Full control over the host execution environment, leading to lateral movement within the infrastructure.
• Service Disruption: Denial of service affecting automation pipelines critical to business operations.
• Reputational Damage: If the compromise affects customer-facing services or leads to data disclosure.

Blast Radius: The EPSS score of 0.00289 (21.1% percentile) indicates low current exploit probability in the wild. However, this does not diminish the severity — the vulnerability class is well-understood, and weaponization is feasible. The lack of CISA KEV listing suggests no confirmed government exploitation.

Detection Guidance

Sigma Rule

title: OpenClaw Environment Variable Injection via Rustup
id: 6f4c9a2e-7d3b-4a8f-9c6e-2b5d8f0a1c3e
status: experimental
description: Detects attempts to inject rustup environment variables into OpenClaw host exec operations
author: Valtersit Threat Intelligence
date: 2026/01/15
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith:
            - '/rustup'
            - '/openclaw'
        CommandLine|contains:
            - 'RUSTUP_TOOLCHAIN='
            - 'RUSTUP_HOME='
            - 'RUSTUP_DIST_SERVER='
            - 'RUSTUP_UPDATE_ROOT='
            - 'RUSTUP_IO_THREADS='
            - 'RUSTUP_TRACE_DIR='
    condition: selection
falsepositives:
    - Legitimate rustup environment configuration by administrators
    - Development environments where rustup variables are intentionally set
level: high

YARA Rule

rule OpenClaw_Rustup_Env_Injection
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects payloads containing rustup environment variable injection patterns"
        cve = "CVE-2026-62203"
        date = "2026-01-15"
    strings:
        $env1 = "RUSTUP_TOOLCHAIN=" ascii wide
        $env2 = "RUSTUP_HOME=" ascii wide
        $env3 = "RUSTUP_DIST_SERVER=" ascii wide
        $env4 = "RUSTUP_UPDATE_ROOT=" ascii wide
        $env5 = "RUSTUP_IO_THREADS=" ascii wide
        $env6 = "RUSTUP_TRACE_DIR=" ascii wide
        $cmd1 = "host exec" ascii wide nocase
        $cmd2 = "rustup" ascii wide nocase
    condition:
        (any of ($env*)) and ($cmd1 or $cmd2)
}

Suricata IDS Rule

alert http any any -> any any (
    msg:"CVE-2026-62203 - OpenClaw Rustup Environment Variable Injection Attempt";
    flow:established,to_server;
    content:"RUSTUP_TOOLCHAIN="; nocase;
    content:"RUSTUP_HOME="; nocase;
    content:"RUSTUP_DIST_SERVER="; nocase;
    content:"RUSTUP_UPDATE_ROOT="; nocase;
    http.request_body;
    classtype:attempted-admin;
    reference:cve,2026-62203;
    sid:2026001;
    rev:1;
)

Elastic Detection

sequence by process.entity_id with maxspan=5s
  [ process where event.type == "start" and process.name == "openclaw" and process.args : "*host*" and process.args : "*exec*" ]
  [ process where event.type == "start" and (
      process.env : "*RUSTUP_TOOLCHAIN=*" or
      process.env : "*RUSTUP_HOME=*" or
      process.env : "*RUSTUP_DIST_SERVER=*" or
      process.env : "*RUSTUP_UPDATE_ROOT=*" or
      process.env : "*RUSTUP_IO_THREADS=*" or
      process.env : "*RUSTUP_TRACE_DIR=*"
  ) ]

Splunk SPL Query

index=main sourcetype=linux:process
(process=rustup OR process=openclaw)
AND (
    env_vars="*RUSTUP_TOOLCHAIN=*" OR
    env_vars="*RUSTUP_HOME=*" OR
    env_vars="*RUSTUP_DIST_SERVER=*" OR
    env_vars="*RUSTUP_UPDATE_ROOT=*" OR
    env_vars="*RUSTUP_IO_THREADS=*" OR
    env_vars="*RUSTUP_TRACE_DIR=*"
)
| stats count by host, user, process, command
| where count > 0
| table _time, host, user, process, command, env_vars
| sort -_time

Wazuh OSSEC Rule

<rule id="202603" level="12">
    <decoded>ossec</decoded>
    <if_sid>5350</if_sid>
    <regex>RUSTUP_(TOOLCHAIN|HOME|DIST_SERVER|UPDATE_ROOT|IO_THREADS|TRACE_DIR)=</regex>
    <description>CVE-2026-62203: OpenClaw rustup environment variable injection detected</description>
    <group>vulnerability,execution,pentest,</group>
    <mitre>
        <id>T1574</id>
    </mitre>
</rule>

Mitigation & Patch Guidance

Patch Confidence: 4/4 — CONFIRMED. Three or more independent sources (NVD, CNA, OSV) confirm that version 2026.6.6 fixes this vulnerability.

1. Immediate Mitigations

• Block untrusted callers: Temporarily restrict access to the host exec functionality to only fully trusted, high-privilege callers until the patch is applied.
• Disable rustup execution: If rustup is not critical to your OpenClaw workflows, prevent OpenClaw from invoking rustup-related binaries.
• Network segmentation: Limit network access to OpenClaw management interfaces to trusted subnets only.
• Audit input paths: Review all configured input paths for potential injection of environment variables.

2. Patch/Upgrade Steps

1. Immediately upgrade to OpenClaw version 2026.6.6 or later.
2. If using a package manager (OSV tracks this vulnerability), apply the fix through your package update channel.
3. Verify the upgrade by checking the version string before and after deployment.
4. After patching, conduct a regression test to confirm the environment variable filter now includes rustup startup variables in its denylist.

3. Long-Term Hardening

• Principle of least privilege: Ensure OpenClaw runs with the minimum necessary user privileges. The CVSS score of 8.8 assumes only low privileges are required for exploitation — reducing OpenClaw's privilege level reduces the impact of successful exploitation.
• Environment variable hygiene: Implement centralized environment variable management to ensure consistent sanitization across all execution contexts.
• Run-time monitoring: Deploy the detection rules above to monitor for environment variable injection attempts.
• Adopt a denylist review process: Regularly audit CWE-184-style incomplete denylists to ensure new environment variables are added to the exclusion list as application dependencies evolve.
• Vulnerability management: Subscribe to OpenClaw security advisories to receive timely patch notifications.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-62203
2. CNA Advisory: OpenClaw Security Advisory — OpenClaw < 2026.6.6 Environment Variable Injection via rustup
3. OSV Entry: OSV vulnerability database reference for CVE-2026-62203 (osv.dev)
4. MITRE CWE: https://cwe.mitre.org/data/definitions/184.html — Incomplete List of Disallowed Inputs
5. MITRE ATT&CK: https://attack.mitre.org/techniques/T1574/ — Hijack Execution Flow (related technique for persistence via environment manipulation)

Threat actor campaigns: No known active campaigns or in-the-wild exploitation has been reported. CISA KEV does not list this CVE. PoC availability is unknown, and no exploit code or Nuclei templates have been published.