---
cve: "CVE-2026-77244"
severity: "CRITICAL"
cvss: 10.0
epss: "0.4%"
vendor: "sooperset"
kev: false
exploited: false
published: "2026-09-22 18:17:17"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-11-09T13:45:35+01:00"
---

# CVE-2026-77244

> 10.0 CRITICAL · 🧪 PoC

## Beschreibung

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the HTTP transport accepts requests without a verified user identity and downstream fetcher construction falls back to the operator's globally configured Jira or Confluence credentials. A network client that can reach the MCP endpoint can invoke Atlassian tools as the operator, including read and write operations available to that account. The advisory traces the vulnerable input and processing flow through UserTokenMiddleware, AtlassianOpaqueTokenVerifier, _get_fetcher, and streamable-http, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

## CNA-Record (Kanon, cvelistV5)

- CNA: **GitHub_M**
- State: PUBLISHED
- Stand: 2026-09-23 14:38:20
- CNA-CVSS: **10.0** (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **total**

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Schwachstellen-Klasse

- **CWE-287** — Improper Authentication
  When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
- **CWE-303** — Incorrect Implementation of Authentication Algorithm
  The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.
- **CWE-862** — Missing Authorization
  The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

## Angriffsmuster (CAPEC)

- [CAPEC-22 — Exploiting Trust in Client](https://capec.mitre.org/data/definitions/22.html) _(Severity: High)_
- [CAPEC-57 — Utilizing REST's Trust in the System Resource to Obtain Sensitive Data](https://capec.mitre.org/data/definitions/57.html) _(Severity: Very High)_
- [CAPEC-114 — Authentication Abuse](https://capec.mitre.org/data/definitions/114.html) _(Severity: Medium)_
- [CAPEC-115 — Authentication Bypass](https://capec.mitre.org/data/definitions/115.html) _(Severity: Medium)_
- [CAPEC-151 — Identity Spoofing](https://capec.mitre.org/data/definitions/151.html) _(Severity: Medium)_
- [CAPEC-194 — Fake the Source of Data](https://capec.mitre.org/data/definitions/194.html) _(Severity: Medium)_
- [CAPEC-593 — Session Hijacking](https://capec.mitre.org/data/definitions/593.html) _(Severity: Very High)_
- [CAPEC-633 — Token Impersonation](https://capec.mitre.org/data/definitions/633.html) _(Severity: Medium)_

## ATT&CK-Techniken

- [T1040 — Network Sniffing](https://attack.mitre.org/techniques/T1040/)
- [T1548 — Abuse Elevation Control Mechanism](https://attack.mitre.org/techniques/T1548/)
- [T1185 — Browser Session Hijacking](https://attack.mitre.org/techniques/T1185/)
- [T1550.001 — Use Alternate Authentication Material:Application Access Tok](https://attack.mitre.org/techniques/T1550/001/)
- [T1563 — Remote Service Session Hijacking](https://attack.mitre.org/techniques/T1563/)
- [T1134 — Access Token Manipulation](https://attack.mitre.org/techniques/T1134/)

## Patch verfügbar (OSV)

- b041733473f95119dd539542a43c280737a8e460 (Commit)

## Referenzen

- <https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wrhw-j3f9-8vc6>
- <https://github.com/sooperset/mcp-atlassian/pull/1448>
- <https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460>
- <https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-77244/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_