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CVE-2026-77244 critical CVSS 10.0

Authentication Bypass in mcp-atlassian (CVE-2026-77244)

Summary

Authentication bypass in mcp-atlassian (CVE-2026-77244). 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.

Description

mcp-atlassian deploys in two common patterns:

Pattern A (single-user, server-side credentials): operator sets
JIRA_USERNAME + JIRA_API_TOKEN (or CONFLUENCE_USERNAME + CONFLUENCE_API_TOKEN)
in environment variables. Server uses these to call Jira/Confluence.
This is the documented quickstart pattern.

Pattern B (multi-user, OAuth or per-request PAT): operator sets up OAuth
proxy or accepts per-user tokens via Authorization or service headers.

The authentication mechanism in HTTP transport has two issues that combine
to permit unauthenticated access to Pattern A deployments:

  1. AtlassianOpaqueTokenVerifier.verify_token() at
    src/mcp_atlassian/utils/token_verifier.py accepts any non-empty string
    as a valid token:

    async def verify_token(self, token: str) -> AccessToken | None:
    if not token:
        return None
    scopes = self.required_scopes or []
    return AccessToken(
        token=token,
        client_id="atlassian",
        scopes=scopes,
        expires_at=int(time.time()) + 86400 * 30,
    )

    The docstring documents this: "we accept non-empty tokens and attach
    the required scopes."

  2. The default deployment does NOT enable the OAuth proxy auth provider
    (OAUTH_PROXY_ENABLE_ENV defaults to false; main.py:726). When
    _build_auth_provider() returns None, FastMCP HTTP transport accepts
    requests with no authentication challenge.

  3. `UserT…

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-2026-77244 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: 10.0/10.
What to do: upgrade mcp-atlassian to 0.22.0 or later.
If unsure, ask your IT team or search "mcp-atlassian CVE-2026-77244" on the vendor's site.

CVE-2026-77244 (mcp-atlassian) — CWE-287 / CVSS v3 10.0
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Authorization header / UserTokenMiddleware._parse_auth_header / user_atlassian_token / JIRA_API_TOKEN
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

Authentication bypass (CWE-287) 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 / UserTokenMiddleware._parse_auth_header / user_atlassian_token / JIRA_API_TOKEN.

🔥 Severity

Severity: Critical (CVSS 10.0/10). 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

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