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OpenClaw CVE-2026-100573

| EUVDEUVD-2026-87478 MEDIUM
Missing Authorization (CWE-862)
2026-09-26 VulnCheck GHSA-v9f5-4mfv-5533
4.8
CVSS 4.0 · Vendor: VulnCheck
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain sandboxed coding-agent session
  2. Exploit
    Enumerate tools via MCP loopback
  3. Execution
    Invoke denied tool bypassing sandbox.tools.deny
  4. Impact
    Access excluded data or perform excluded action

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization checks on every request
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires an already-running sandboxed coding-agent session in OpenClaw with an MCP loopback component active and an operator-defined sandbox.tools.deny policy in place. The attacker must be able to drive that sandboxed session (local access to the session context, e.g., via a steered/malicious agent task) - this is not remotely reachable without such a session, hence AV:L and PR:L. Impact is limited by exactly which tools the operator denied: a deny-list of benign tools yields minor exposure, while denied high-capability tools raise the stakes. No user interaction beyond the attacker's own session control is needed. Fixed in 2026.8.1.

Impact

This is a genuinely low-priority issue despite carrying a 'sandbox bypass' label. The vendor CVSS 4.0 vector (AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N, base 4.8) tells the real story: exploitation is LOCAL (the attacker must already possess a sandboxed coding-agent session), requires low privileges within that session, and yields only LOW confidentiality impact per the vendor. There is no EPSS score, no CISA KEV listing, and no public exploit code identified at time of analysis, so all threat-intelligence signals point to no observed or predicted exploitation. The vulnerability is a policy-enforcement gap (CWE-862 Missing Authorization) rather than a memory-safety or RCE flaw. One tension worth noting: the vendor scored VI:N/VA:N (no integrity/availability impact), yet the description explicitly states attackers can 'perform actions the operator intended to exclude' - invoking denied tools plausibly carries at least low integrity impact, which I reflect in my independent assessment. The real-world risk ceiling is entirely determined by WHICH tools the operator placed in sandbox.tools.deny; the CVE abstracts that away, so the '4.8' is a floor for a benign deny-list and could be higher where dangerous tools were denied. Net: not a fire-drill; patch on normal cadence.

Exploit ScenarioDerived

An attacker who already controls or influences a sandboxed coding-agent session (e.g., via a malicious prompt/task steering the agent) uses the MCP loopback path to enumerate and call tools the operator explicitly placed on the sandbox.tools.deny list, reaching data or capabilities meant to be walled off from the sandbox. No public exploit code exists; exploitation is local to an existing sandbox session and constrained by which tools were denied.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 26, 2026

Sandbox policy bypass in OpenClaw before 2026.8.1 allows a sandboxed coding-agent session to list and invoke tools that the operator explicitly placed on the sandbox.tools.deny list, because the MCP loopback path does not enforce the same tool-exclusion policy as the normal tool-invocation path. The flaw is local in nature (CVSS 4.0 AV:L/PR:L) and requires an already-running sandboxed session with an active MCP loopback component and a configured deny policy, so practical exposure is bounded by exactly which tools an operator chose to deny - a benign deny-list yields minor exposure, while denied high-capability tools raise the stakes. No public exploit code has been identified at time of analysis, and the vendor has released a fix in 2026.8.1.

RemediationAI

Upgrade OpenClaw to 2026.8.1 or later - this is the vendor-released fix and the only complete resolution - using the guidance in GHSA-5m4g-88rg-69pj (https://github.com/openclaw/openclaw/security/advisories/GHSA-5m4g-88rg-69pj) and the VulnCheck advisory (https://www.vulncheck.com/advisories/openclaw-before-2026.8.1-sandbox-policy-bypass-via-mcp-loopback). Where immediate patching is not possible, treat sandbox.tools.deny as non-binding for MCP loopback sessions: do not rely on deny-listing alone to fence off powerful tools, and instead remove the credentials, filesystem paths, network reachability, or upstream service permissions those denied tools would need, accepting that this reduces agent functionality. Disabling the MCP loopback component (or the sandboxed tool-invocation feature entirely) eliminates the bypass but breaks agent tool use, so scope it to untrusted or externally steered sessions only. Additionally, restrict who or what can drive a sandboxed session, since the flaw requires an attacker-controlled agent task inside a running session, and enable tool-invocation logging to detect attempts to enumerate or call denied tools. Given the low assessed severity, these compensating controls are adequate interim measures rather than an emergency response.

Affected VersionsENISA

OpenClaw 0 <2026.8.1

Affected Packages

euvd openclaw fix: 2026.8.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

OpenClaw is a coding-agent platform that runs agent sessions inside a sandbox and constrains the tools those sessions may call through an operator-defined sandbox.tools.deny policy. Tool invocation is brokered over MCP (Model Context Protocol); the affected code is the MCP loopback component, which is intended to let the agent reach local tool services. CWE-862 (Missing Authorization) is the right root-cause class here: authorization for the deny-list is enforced on one code path but not on the loopback path, so a session that should have been blocked from a denied tool can still enumerate and invoke it. This is a policy-enforcement gap rather than a memory-safety or injection bug - there is no privilege escalation beyond the privileges the agent session already holds, and no remote reachability. The independent assessment scores it CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N, i.e. low confidentiality and low integrity impact with local access and low privileges required, which is consistent with the CVSS 4.0 vector's AV:L/PR:L and low confidentiality impact. The CPE cpe:2.3:a:openclaw:openclaw:*:*:*:*:*:*:*:* and the EUVD affected-version data both confirm that all OpenClaw releases prior to 2026.8.1 are in scope.

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Severity by source

Vendor (VulnCheck) PRIMARY 4.8 MEDIUM
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 4.4 MEDIUM

Local to an existing sandboxed session (AV:L, PR:L); low complexity; C:L and I:L because denied tools can both read data and perform excluded actions, impact bounded by the deny-list contents.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

1
Patch available
Sep 26, 2026 - 03:01 EUVD

DescriptionCVE.org

OpenClaw versions before 2026.8.1 contain a sandbox policy bypass vulnerability in the MCP loopback component that allows sandboxed coding-agent sessions to invoke tools explicitly denied by sandbox.tools.deny policy. Attackers can list and invoke denied tools to access data or perform actions the operator intended to exclude from the sandbox.

Threat Intelligence Overview

EPSS Score
0.1%
Top 99% exploitable
Prevalence
Low
niche open-source Node.js AI agent framework, no broad enterprise footprint
Data Quality
5 sources
Confidence: Medium
EUVD NVD CVE.org EPSS Vulnrichment GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0
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