SSRF (Server-Side Request Forgery) in mcp-atlassian (CVE-2026-77249)
Summary
SSRF in mcp-atlassian (CVE-2026-77249). Risk of unauthorized operations or information disclosure. Exploitable via GET /rest/api/2/user/search. Mitigation: upgrade to 0.22.0 or later.
Original description
The description as published by the source.
Summary
The fix for the SSRF vulnerability tracked as GHSA-7r34-79r5-rcc9 / CVE-2026-27826 is incomplete. That fix added two defenses: validate_url_for_ssrf() on the per-request X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers (blocking a directly-internal base URL), and a redirect-validation hook (_make_ssrf_safe_hook) attached to the fetcher's HTTP session so that an attacker-controlled public host cannot redirect outbound requests to an internal address.
However, one outbound request path does not go through the hooked session. JiraUserMixin._lookup_user_by_permissions issues its request with the module-level requests.get instead of self.jira._session.get, so the redirect-validation hook never runs for it. An unauthenticated attacker (in the HTTP / multi-tenant transport mode that binds 0.0.0.0 with no credentials) can therefore set a public base URL that passes validate_url_for_ssrf(), then have their own server return an HTTP redirect to an internal address. The bare requests.get follows that redirect with no validation, resulting in a blind server-side request to an arbitrary internal host and port.
Affected component
src/mcp_atlassian/jira/users.py, method _lookup_user_by_permissions (the requests.get(...) call):
url = f"{self.config.url}/rest/api/2/user/permission/search"
params = {"query": username, "permissions": "BROWSE"}
...
response = requests.get( # module-level requests, NOT self.jira._session
url,
params=…
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-2026-77249 has been found in mcp-atlassian.
Attackers can target a specific entry point like GET /rest/api/2/user/search over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade mcp-atlassian to 0.22.0 or later.
If unsure, ask your IT team or search "mcp-atlassian CVE-2026-77249" on the vendor's site.
CVE-2026-77249 (mcp-atlassian) — CWE-918 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /rest/api/2/user/search / GET /rest/api/2/user/permission/search
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.
SSRF (CWE-918) exists in mcp-atlassian. Attackers reach the vulnerable code path via GET /rest/api/2/user/search without authentication.
Check the vendor advisory for the affected versions of mcp-atlassian. Attack surface: GET /rest/api/2/user/search / GET /rest/api/2/user/permission/search.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 0.22.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual GET /rest/api/2/user/search requests with malformed payloads or SQL meta-characters. 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
-
1Identify 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。 -
2Hunt for indicators of compromise detect
grep 'GET /rest/api/2/user/search' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
GET /rest/api/2/user/searchへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply 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と、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against GET /rest/api/2/user/search on staging to confirm patch closes the vector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 Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
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