PT-2026-44123 · Toolbox · Toolbox

Deeven-Seru · Published 2026-05-27 · Updated 2026-05-31 · CVE-2026-9739

Positive Technologies (AI Summary)

CVSS v4.0

9.4

Critical

Base vector

AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Name of the Vulnerable Software and Affected Versions Toolbox (affected versions not specified)

Description The software is susceptible to DNS rebinding attacks when using Server-Sent Events (SSE) under specification v2024-11-05. This occurs because the SSE initialization handler retains a hardcoded Access-Control-Allow-Origin: * header, which bypasses the security provided by the allowed-origins and allowed-hosts flags implemented to align with Model Context Protocol (MCP) security guidelines.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Weakness Enumeration

CWE-942

Related Identifiers

CVE-2026-9739

Affected Products

Toolbox

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-9739 · Security Note
• https://github.com/googleapis/mcp-toolbox/issues/3053 · Note
• https://github.com/googleapis/mcp-toolbox/pull/3054 · Note
• https://t.me/CVEtracker/55194 · Telegram Post
• https://twitter.com/PurpleOps_io/status/2061158799457558615 · Twitter Post
• https://twitter.com/VulmonFeeds/status/2059925927140765763 · Twitter Post