SSRF (Server-Side Request Forgery) in mcp-atlassian (CVE-2026-77265)
Summary
SSRF in mcp-atlassian (CVE-2026-77265). Confidential information can be exposed externally. Exploitable via Host header. Mitigation: upgrade to 0.22.0 or later.
Original description
The description as published by the source.
Summary
The SSRF protection for header-based authentication uses a validate-then-use pattern vulnerable to DNS rebinding. validate_url_for_ssrf resolves the hostname via DNS and checks that the resolved IP is globally routable. However, the actual HTTP request happens later, during which the DNS record may have changed to point to an internal IP (127.0.0.1, 169.254.169.254, etc.). The SSRF redirect hook only validates redirect targets, not the initial connection.
Details
The vulnerability spans main.py (validation) and dependencies.py (use).
Step 1 -- URL validation at middleware time:
In src/mcp_atlassian/servers/main.py:524-531, the URL from X-Atlassian-Jira-Url is validated:
if jira_url_str:
ssrf_error = validate_url_for_ssrf(jira_url_str)
if ssrf_error:
# blocked
validate_url_for_ssrf (src/mcp_atlassian/utils/urls.py:113-116) resolves DNS and checks is_global:
dns_error = _check_dns_resolution(hostname)
if dns_error:
return dns_error
Step 2 -- HTTP request happens later with a separate DNS resolution:
In src/mcp_atlassian/servers/dependencies.py:544-562, a JiraFetcher is created with the attacker URL and makes HTTP requests to it. The SSRF redirect hook (attach_ssrf_hook=True) is applied but only checks redirect Location headers, not the initial connection target.
DNS rebinding timeline:
- Attacker sets up rebind.attacker.com with short TTL (1 second)
- First DNS resolution (validate_url_for_s…
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-2026-77265 has been found in mcp-atlassian.
Attackers can target a specific entry point like Host header over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 5.9/10.
What to do: upgrade mcp-atlassian to 0.22.0 or later.
If unsure, ask your IT team or search "mcp-atlassian CVE-2026-77265" on the vendor's site.
CVE-2026-77265 (mcp-atlassian) — CWE-918 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Host header
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 Host header without authentication.
Check the vendor advisory for the affected versions of mcp-atlassian. Attack surface: Host header.
Severity: Medium (CVSS 5.9/10). Confidential information can be exposed externally.
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 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
-
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。 -
2Apply 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。
-
3Post-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
References
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com
- web github.com