Vulnerability-Lookup

GHSA-CC5H-2PWP-PVCC

Vulnerability from github – Published: 2026-09-22 20:34 – Updated: 2026-09-22 20:34

Summary

MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport

Details

Summary

In the documented multi-user HTTP deployment (--transport streamable-http with global operator Atlassian credentials), sooperset/mcp-atlassian exposes all tools to unauthenticated network clients, and the upload_attachment tool reads an attacker-supplied file_path with no path validation. Chained, an unauthenticated network attacker reads arbitrary files on the MCP server host (e.g. /proc/self/environ → the operator's Atlassian API token + .env secrets, ~/.ssh/id_rsa, /etc/passwd) by uploading them to an attacker-chosen page/issue and reading them back.

Details

Missing authentication (transport): - streamable-http binds 0.0.0.0 by default (src/mcp_atlassian/__init__.py:151). - The OAuth-proxy auth provider is opt-in (ATLASSIAN_OAUTH_PROXY_ENABLE, default false), so main_mcp is built with auth=None (src/mcp_atlassian/servers/main.py:724-731, 813-817). - UserTokenMiddleware._parse_auth_header sets auth_validation_error only for a malformed Authorization header; a request with no Authorization header passes through (main.py:416-446, 582-595). - _get_fetcher then falls through to the global credential fallback using the operator's .env Atlassian token (src/mcp_atlassian/servers/dependencies.py:644-676). check_write_access gates only on read-only mode, not auth → read and write tools reachable.

Arbitrary file read (sink): - upload_attachment's file_path flows unsanitized into open(file_path, 'rb') — Confluence src/mcp_atlassian/confluence/attachments.py:477 (from servers/confluence.py:1294-1369); Jira src/mcp_atlassian/jira/attachments.py:386 (from servers/jira.py:1609-1673). No validate_safe_path / allowlist (contrast the download flow, hardened after CVE-2026-27825).

Proof of Concept

# unauthenticated (no Authorization header) against a default streamable-http deployment:
tools/call upload_attachment { "file_path": "/proc/self/environ", "page_id": "<attacker-chosen>" }
# then read it back:
tools/call download_attachment { ... }   # returns the bytes (base64) -> operator's ATLASSIAN token + .env secrets

Impact

Unauthenticated arbitrary local file read on the MCP server host — including the operator's Atlassian API token and .env secrets — a boundary the Atlassian-scoped tool must not cross, plus unauthenticated use of every read/write Atlassian tool as the operator's (often admin) principal. Distinct from GHSA-xjgw-4wvw-rgm4 (file write via download_path) and GHSA-7r34-79r5-rcc9 (URL-header SSRF).

Suggested fix

Require authentication on the streamable-http transport by default (do not fall back to operator global credentials for unauthenticated requests); apply validate_safe_path/allowlist to file_path in upload_attachment as the download flow already does.

Affected

mcp-atlassian <= 0.21.1.

Severity

8.6 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "mcp-atlassian"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.22.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-77248"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-22T20:34:43Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\nIn the documented multi-user HTTP deployment (`--transport streamable-http` with global operator Atlassian credentials), sooperset/mcp-atlassian exposes all tools to **unauthenticated network clients**, and the `upload_attachment` tool reads an attacker-supplied `file_path` with **no path validation**. Chained, an unauthenticated network attacker reads arbitrary files on the MCP server host (e.g. `/proc/self/environ` \u2192 the operator\u0027s Atlassian API token + `.env` secrets, `~/.ssh/id_rsa`, `/etc/passwd`) by uploading them to an attacker-chosen page/issue and reading them back.\n\n### Details\n**Missing authentication (transport):**\n- streamable-http binds `0.0.0.0` by default (`src/mcp_atlassian/__init__.py:151`).\n- The OAuth-proxy auth provider is opt-in (`ATLASSIAN_OAUTH_PROXY_ENABLE`, default false), so `main_mcp` is built with `auth=None` (`src/mcp_atlassian/servers/main.py:724-731, 813-817`).\n- `UserTokenMiddleware._parse_auth_header` sets `auth_validation_error` only for a *malformed* Authorization header; a request with **no** Authorization header passes through (`main.py:416-446, 582-595`).\n- `_get_fetcher` then falls through to the global credential fallback using the operator\u0027s `.env` Atlassian token (`src/mcp_atlassian/servers/dependencies.py:644-676`). `check_write_access` gates only on read-only mode, not auth \u2192 read **and** write tools reachable.\n\n**Arbitrary file read (sink):**\n- `upload_attachment`\u0027s `file_path` flows unsanitized into `open(file_path, \u0027rb\u0027)` \u2014 Confluence `src/mcp_atlassian/confluence/attachments.py:477` (from `servers/confluence.py:1294-1369`); Jira `src/mcp_atlassian/jira/attachments.py:386` (from `servers/jira.py:1609-1673`). No `validate_safe_path` / allowlist (contrast the download flow, hardened after CVE-2026-27825).\n\n### Proof of Concept\n```\n# unauthenticated (no Authorization header) against a default streamable-http deployment:\ntools/call upload_attachment { \"file_path\": \"/proc/self/environ\", \"page_id\": \"\u003cattacker-chosen\u003e\" }\n# then read it back:\ntools/call download_attachment { ... }   # returns the bytes (base64) -\u003e operator\u0027s ATLASSIAN token + .env secrets\n```\n\n### Impact\nUnauthenticated arbitrary local file read on the MCP server host \u2014 including the operator\u0027s Atlassian API token and `.env` secrets \u2014 a boundary the Atlassian-scoped tool must not cross, plus unauthenticated use of every read/write Atlassian tool as the operator\u0027s (often admin) principal.  Distinct from GHSA-xjgw-4wvw-rgm4 (file *write* via download_path) and GHSA-7r34-79r5-rcc9 (URL-header SSRF). \n\n### Suggested fix\nRequire authentication on the streamable-http transport by default (do not fall back to operator global credentials for unauthenticated requests); apply `validate_safe_path`/allowlist to `file_path` in `upload_attachment` as the download flow already does.\n\n### Affected\n`mcp-atlassian` \u003c= 0.21.1.",
  "id": "GHSA-cc5h-2pwp-pvcc",
  "modified": "2026-09-22T20:34:43Z",
  "published": "2026-09-22T20:34:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-cc5h-2pwp-pvcc"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sooperset/mcp-atlassian/pull/1448"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sooperset/mcp-atlassian"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport"
}

CVE-2026-77248 (GCVE-0-2026-77248)

Vulnerability from cvelistv5 – Published: 2026-09-22 18:49 – Updated: 2026-09-24 15:23

Title

MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport

Summary

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Severity

8.6 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-24 15:23 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-306 - Missing Authentication for Critical Function

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/sooperset/mcp-atlassian/securi…	x_refsource_CONFIRM
https://github.com/sooperset/mcp-atlassian/pull/1448	x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/commit…	x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/releas…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
sooperset	mcp-atlassian	Affected: < 0.22.0

Show details on NVD website

JSON

To clipboard

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          "value": "MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0."
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

GHSA-CC5H-2PWP-PVCC

Summary

Details

Proof of Concept

Impact

Suggested fix

Affected

CVE-2026-77248 (GCVE-0-2026-77248)

Tags

Sightings

Nomenclature

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