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CVE-2026-77248 high CVSS 8.6

Path Traversal in mcp-atlassian (CVE-2026-77248)

Summary

Path traversal in mcp-atlassian (CVE-2026-77248). Confidential information can be exposed externally. Exploitable via Authorization header. Mitigation: upgrade to 0.22.0 or later.

Original description

The description as published by the source.

Summary

In the documented multi-user HTTP deployment (--transport streamable-http with global operator Atlassian credentials), sooperset/mcp-atlassian exposes all tools to unauthenticated network clients, and the upload_attachment tool reads an attacker-supplied file_path with no path validation. Chained, an unauthenticated network attacker reads arbitrary files on the MCP server host (e.g. /proc/self/environ → the operator's Atlassian API token + .env secrets, ~/.ssh/id_rsa, /etc/passwd) by uploading them to an attacker-chosen page/issue and reading them back.

Details

Missing authentication (transport):

  • streamable-http binds 0.0.0.0 by default (src/mcp_atlassian/__init__.py:151).
  • The OAuth-proxy auth provider is opt-in (ATLASSIAN_OAUTH_PROXY_ENABLE, default false), so main_mcp is built with auth=None (src/mcp_atlassian/servers/main.py:724-731, 813-817).
  • UserTokenMiddleware._parse_auth_header sets auth_validation_error only for a malformed Authorization header; a request with no Authorization header passes through (main.py:416-446, 582-595).
  • _get_fetcher then falls through to the global credential fallback using the operator's .env Atlassian token (src/mcp_atlassian/servers/dependencies.py:644-676). check_write_access gates only on read-only mode, not auth → read and write tools reachable.

Arbitrary file read (sink):

  • upload_attachment's file_path flows unsanitized into `open(file_path, '…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-77248 has been found in mcp-atlassian.
Attackers can target a specific entry point like Authorization header over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.6/10.
What to do: upgrade mcp-atlassian to 0.22.0 or later.
If unsure, ask your IT team or search "mcp-atlassian CVE-2026-77248" on the vendor's site.

CVE-2026-77248 (mcp-atlassian) — CWE-22 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Authorization header / upload_attachment / file_path / ATLASSIAN_OAUTH_PROXY_ENABLE
Patched: 0.22.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Path traversal (CWE-22) exists in mcp-atlassian. Attackers reach the vulnerable code path via Authorization header without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of mcp-atlassian. Attack surface: Authorization header / upload_attachment / file_path / ATLASSIAN_OAUTH_PROXY_ENABLE.

🔥 Severity

Severity: High (CVSS 8.6/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 0.22.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'mcp-atlassian' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'mcp-atlassian' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で mcp-atlassian を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade mcp-atlassian to 0.22.0

    ステージング環境で 0.22.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

pip mcp-atlassian
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0"}]}]
PyPI mcp-atlassian
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0"}]}]

References

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