Claude Dispatch "ThisBash": any browser extension on claude.ai can make Claude Desktop run code, and Anthropic won't fix it
Published Sources: pwn.watch
What is affected, what to do
Forever Security researcher Gal Weizman found that Claude Dispatch, the feature that sends tasks from phone or browser to the Claude Desktop agent, is reachable from an ordinary logged-in claude.ai web session. A browser extension that can run scripts on claude.ai can look up the user's Claude Desktop Dispatch session with the user's own cookies, push prompts into it until the agent complies, and auto-click Allow on approval prompts, getting the desktop agent to run commands such as installing a malicious npm package.
The available sources name no fixed version. Check the vendor guidance and the linked original advisory.
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
—
XIEM Effective CVSS
No value is available for this vulnerability.
—
CVSS v3
No value is available for this vulnerability.
—
EPSS score
No value is available for this vulnerability.
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 30.00 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Forever Security researcher Gal Weizman found that Claude Dispatch, the feature that sends tasks from phone or browser to the Claude Desktop agent, is reachable from an ordinary logged-in claude.ai web session. A browser extension that can run scripts on claude.ai can look up the user's Claude Desktop Dispatch session with the user's own cookies, push prompts into it until the agent complies, and auto-click Allow on approval prompts, getting the desktop agent to run commands such as installing a malicious npm package. Because Dispatch works across machines, a compromised browser on one computer can reach Claude Desktop on another computer signed into the same Claude account, for example a work laptop logged into a personal account. Anthropic accepted the report in May, closed it as a duplicate of a known issue, issued no CVE and said it planned to retire Dispatch at the end of October; as of Oct 30 its support page still listed Dispatch in limited beta for existing users. Weizman says the same design weakness also exists in Claude Code Remote Control and Claude Cowork sessions on the web. The attack needs a malicious or hijacked extension with access to claude.ai and the user signed in to both claude.ai and Claude Desktop.
Source: pwn.watch