CRITICAL CVSS 9.0
Published: 2026-03-10

CVE-2026-27825

mcp-atlassian mcp_atlassian Security Advisory (CVE-2026-27825)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-27825 impacting mcp-atlassian mcp_atlassian. Evaluated with CVSS Base Score of 9.0 (CRITICAL).

Original NVD Description

Source: NIST NVD
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, the `confluence_download_attachment` MCP tool accepts a `download_path` parameter that is written to without any directory boundary enforcement. An attacker who can call this tool and supply or access a Confluence attachment with malicious content can write arbitrary content to any path the server process has write access to. Because the attacker controls both the write destination and the written content (via an uploaded Confluence attachment), this constitutes for arbitrary code execution (for example, writing a valid cron entry to `/etc/cron.d/` achieves code execution within one scheduler cycle with no server restart required). Version 0.17.0 fixes the issue.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Adjacent (AV:A)
Requires shared subnet / local network access
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product mcp-atlassian / mcp_atlassian
Affected Versions *
Weakness Enumeration CWE-22

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-27825 impacting mcp-atlassian mcp_atlassian.

⚡ Nuclei Detection Template (YAML) cve-2026-27825.yaml
id: cve-2026-27825

info:
  name: mcp-atlassian mcp_atlassian - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2026-27825 affecting mcp-atlassian mcp_atlassian.
    Evaluation: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, the `confluence_download...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-27825
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 9.0
    cve-id: CVE-2026-27825
    cwe-id: CWE-22
  tags: cve,cve-2026-27825,mcp-atlassian,mcp_atlassian,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "mcp_atlassian"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-27825.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-27825
# Target: mcp-atlassian mcp_atlassian | CVSS: 9.0 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-27825 (mcp-atlassian mcp_atlassian)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against mcp-atlassian mcp_atlassian scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-27825.sh
# Recommended Remediation & Patching Commands for CVE-2026-27825
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install mcp_atlassian 2>/dev/null || \
sudo dnf upgrade mcp_atlassian 2>/dev/null || \
sudo yum update mcp_atlassian

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i mcp_atlassian 2>/dev/null || rpm -qa | grep -i mcp_atlassian

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-27825 in mcp-atlassian mcp_atlassian?

Review vendor-specific security notices and update mcp-atlassian mcp_atlassian packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-27825?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-27825?

CVE-2026-27825 is classified with a CVSS 3.1 Base Score of 9.0 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.0
CRITICAL SEVERITY
CVE ID CVE-2026-27825
Weakness CWE-22
Vendor mcp-atlassian
Product mcp_atlassian
Published 2026-03-10
Vector CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H