CVE-2026-81093 — HIGH (8.6)

Vulnerability Description

The get-html-skeleton tool fetched a URL the caller supplied after checking only its syntax. The handler in src/tools/common/get_html_skeleton.ts validated the url argument with isValidHttpUrl from src/utils/generic.ts, which confirmed the string began with an http or https scheme and parsed as a URL and inspected neither the host name nor the address it resolves to. Loopback, link-local and private ranges therefore passed, including the address cloud providers use to serve instance metadata. The unchecked URL was handed to the web-browser actor and the fetched document was returned in the tool response, so any caller of the MCP server could make it request an endpoint reachable only from the host and read the result, including instance credentials. Version 0.9.12 removes the tool.

CVSS Score

8.6

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality

HIGH

Integrity

NONE

Availability

NONE

Related Weaknesses (CWE)

CWE-918

References

FAQ

What is CVE-2026-81093?

CVE-2026-81093 is a vulnerability with a CVSS score of 8.6 (HIGH). The get-html-skeleton tool fetched a URL the caller supplied after checking only its syntax. The handler in src/tools/common/get_html_skeleton.ts validated the url argument with isValidHttpUrl from sr...

How severe is CVE-2026-81093?

CVE-2026-81093 has been rated HIGH with a CVSS base score of 8.6/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-81093?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.