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VulnerabilityPublished

mcp-atlassian · FastMCP: Post-transform component authorization is skipped on direct calls

Affects mcp-atlassianSource GCVE Database

0

CVSS 6.8 Medium : upgrade to 0.23.1_2 when convenient.

Data as of 30 Oct 2026, 08:31 UTC

CVSS 3.1 base score
6.8Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.23.1_2
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

What to do

Upgrade mcp-atlassian to 0.23.1_2.

Affected software

ProductAffectedFixed in
Homebrewmcp-atlassianpkg:brew/mcp-atlassianOther threatsAffected
  • >=0.23.0 <0.23.1_2
Fixed in
  • 0.23.1_2

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

AI-suggested

A fix is available in FastMCP versions 3.4.10 and 4.1.2 that ensures authorization is applied to the final transformed component in all direct resolution and execution paths. Until upgrading, users should avoid overlapping proxy templates for protected resources and enforce authorization at the handler or server boundary rather than relying solely on component policies affected by transforms.

Description

FastMCP versions 3.0.0 through 3.4.9 and 4.0.0 through 4.1.1 contain an authorization vulnerability where direct calls to transformed components skip the final authorization check. This allows low-privilege users to invoke protected tools, resources, templates, or prompts that should be denied by policy. The issue arises because transforms modify component metadata but the authorization check is performed on the original component, not the transformed one. Fixes are available in FastMCP versions 3.4.10 and 4.1.2. Until patched, users should avoid overlapping proxy templates for protected resources and enforce authorization at the handler or server boundary.

References

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