Sign in Sign up
JA · EN · FR
SecPulse
Categories
CVE-2026-77268 medium CVSS 5.5

Vulnerability in mcp-atlassian (CVE-2026-77268)

Summary

Vulnerability in mcp-atlassian (CVE-2026-77268). Confidential information can be exposed externally. Exploitable via _save_tokens_to_file. Mitigation: upgrade to 0.22.0 or later.

Original description

The description as published by the source.

Summary

The OAuth token fallback file storage in OAuthConfig._save_tokens_to_file() creates token files containing access tokens, refresh tokens, and cloud IDs with default filesystem permissions (typically 0644 on Linux, world-readable). Any local user on a shared system can read these files to obtain full Atlassian API credentials, enabling unauthorized access to the victim's Jira and Confluence data.

Details

The vulnerability exists in src/mcp_atlassian/utils/oauth.py in the _save_tokens_to_file method.

Step 1 -- Directory created without restrictive permissions:

At line 402-403, the token directory is created with mkdir(exist_ok=True) which uses the default umask (typically creating directories with mode 0755):

# src/mcp_atlassian/utils/oauth.py:402-403
token_dir = Path.home() / ".mcp-atlassian"
token_dir.mkdir(exist_ok=True)

Step 2 -- Token file written with default permissions:

At line 417-418, the token file containing sensitive credentials is written using open() with no explicit mode, inheriting default umask permissions (typically 0644 on Linux):

# src/mcp_atlassian/utils/oauth.py:406-418
token_path = token_dir / f"oauth-{self.client_id}.json"

if token_data is None:
    token_data = {
        "refresh_token": self.refresh_token,
        "access_token": self.access_token,
        "expires_at": self.expires_at,
        "cloud_id": self.cloud_id,
        "base_url": self.base_url,
    }

with open(token_pa…

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-2026-77268 has been found in mcp-atlassian.
Attackers can target a specific entry point like _save_tokens_to_file over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 5.5/10.
What to do: upgrade mcp-atlassian to 0.22.0 or later.
If unsure, ask your IT team or search "mcp-atlassian CVE-2026-77268" on the vendor's site.

CVE-2026-77268 (mcp-atlassian) — CWE-732 / CVSS v3 5.5
Attack vector: local / no user interaction
Attack surface: _save_tokens_to_file / access_token / refresh_token / cloud_id
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

A vulnerability (CWE-732) exists in mcp-atlassian. Attackers reach the vulnerable code path via _save_tokens_to_file.

📍 Affected scope

Check the vendor advisory for the affected versions of mcp-atlassian. Attack surface: _save_tokens_to_file / access_token / refresh_token / cloud_id.

🔥 Severity

Severity: Medium (CVSS 5.5/10). 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"}]}]

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details