Path Traversal in mcp-atlassian (CVE-2026-77271)
Summary
Path traversal in mcp-atlassian (CVE-2026-77271). Successful exploitation can lead to full system takeover. Exploitable via base_dir. Mitigation: upgrade to 0.22.0 or later.
Original description
The description as published by the source.
Summary
The path traversal fix introduced in v0.17.0 (GHSA-xjgw-4wvw-rgm4) is incomplete. validate_safe_path() is called without an explicit base_dir, defaulting to os.getcwd(). In standard container deployments the process CWD is the application directory (e.g. /app), so paths within that directory, including the application's own Python source modules, pass validation without
raising an exception. An attacker can overwrite a module file and achieve remote code execution on the next process restart. Versions >= 0.17.0 are not fully patched as stated in the original advisory. Confirmed on v0.21.0 (latest).
Details
src/mcp_atlassian/utils/io.py — validate_safe_path() defaults to CWD when no base_dir is supplied:
def validate_safe_path(path, base_dir=None) -> Path:
if base_dir is None:
base_dir = os.getcwd() # root of the issue
resolved_base = Path(base_dir).resolve(strict=False)
...
if not resolved_path.is_relative_to(resolved_base):
raise ValueError("Path traversal detected")
Both call sites in src/mcp_atlassian/confluence/attachments.py omit base_dir:
validate_safe_path(target_path) # line ~227, download_attachment()
validate_safe_path(target_dir) # line ~270, download_content_attachments()
When the process CWD is /app, any path under /app satisfies is_relative_to(CWD) and passes the guard, including all Python source modules:
/app/src/mcp_atlassian/confluence/a…
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-2026-77271 has been found in mcp-atlassian.
Attackers can target a specific entry point like base_dir over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade mcp-atlassian to 0.22.0 or later.
If unsure, ask your IT team or search "mcp-atlassian CVE-2026-77271" on the vendor's site.
CVE-2026-77271 (mcp-atlassian) — CWE-22 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: base_dir / uvx / validate_safe_path
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.
Path traversal (CWE-22) exists in mcp-atlassian. Attackers reach the vulnerable code path via base_dir.
Check the vendor advisory for the affected versions of mcp-atlassian. Attack surface: base_dir / uvx / validate_safe_path.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
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