CVE-2026-77254

9.1 CRITICAL 0.6% exploit odds Fix listed Auth & access Server

What it is

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, requests to the HTTP MCP endpoint without a per-user identity are allowed to reach tool handlers, which then use globally configured Jira or Confluence credentials. A network caller can perform operations with the operator account's permissions unless the deployment has an independent authentication boundary. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, _get_fetcher, and global credentials, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure, data tampering.
Exploit odds: 0.6% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-08-20 19:02 UTC ReservedThe CVE id was reserved by its CNA
2026-09-22 19:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-09-28 13:22 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.6% in the next 30 days (EPSS).
Severity: 9.1 CRITICAL (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-09-22 19:16 UTC
Last modified: 2026-09-28 13:22 UTC
Exploit probability: 0.6% · EPSS, next 30 days
Weakness: CWE-306 · Missing authentication
Record status: Analyzed

Affected

mcp-atlassian Mcp Atlassian < 0.22.0

Attack profile CVSS 3.1 · 9.1

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-77254.md and follow it. Check whether this project is affected by CVE-2026-77254. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record