Skip to main content
VulnerabilityPublished Updated

Mcp atlassian: FastMCP Auth Integration Allows for Confused Deputy Account Takeover

Affects mcp-atlassianSource GCVE Database

0

CVSS 7.3 High : upgrade to 0.11.11 soon.

Data as of 30 Oct 2026, 08:29 UTC

CVSS 4.0 base score
7.3High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.11.11
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

What to do

Upgrade mcp-atlassian to 0.11.11.

Affected software

ProductAffectedFixed in
Homebrewmcp-atlassianpkg:brew/mcp-atlassianOther threatsAffected
  • >=0.11.9 <0.11.11
Fixed in
  • 0.11.11

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available in FastMCP version 0.11.11 that addresses this vulnerability. Users should upgrade to version 0.11.11 or later to remediate the issue. No additional mitigation actions are specified or required beyond applying the official fix.

Description

FastMCP's authentication integration with Entra ID allows the MCP server to act both as an OAuth client and an authorization server. Due to Entra ID's lack of support for Dynamic Client Registration, the FastMCP server uses a static app registration for authorization. After a user consents to this static client, Entra ID sets a persistent authorization cookie. An attacker controlling their own MCP client can exploit this by initiating authorization flows that reuse the victim's consented static client ID, potentially leading to account takeover. This vulnerability affects FastMCP versions from 0.11.9 up to but not including 0.11.11 and has a CVSS 4.0 score of 7.3 (high severity). A patch is available in version 0.11.11.

References

Community reviews

Loading reviews…