CVE-2026-77269: MCP Atlassian — MEDIUM

Q: Is CVE-2026-77269 actively exploited?

No confirmed active exploitation of CVE-2026-77269 has been reported, but organizations should still patch proactively.

Q: How to fix CVE-2026-77269?

Update to patched version: MCP Atlassian 0.22.0.

Q: What is the CVSS score for CVE-2026-77269?

CVE-2026-77269 has a CVSS v3.1 base score of 6.5 (MEDIUM).

### Summary The `confluence_upload_attachment` and `confluence_upload_attachments` MCP tools accept a `file_path` parameter and do not validate that the path is confined to an allowed directory before opening the file. An attacker who can call these tools can read any file accessible to the MCP...

Full CISO analysis pending enrichment.

What systems are affected?

Package	Ecosystem	Vulnerable Range	Patched
MCP Atlassian	pip	< 0.22.0	`0.22.0`
1 dependents 85% patched ~3d to patch Full package profile →

Do you use MCP Atlassian? You're affected.

How severe is it?

CVSS 3.1

6.5 / 10

EPSS

N/A

Exploitation Status

No known exploitation

Sophistication

N/A

What is the attack surface?

AV Network

AC Low

PR Low

UI None

S Unchanged

C High

I None

A None

What should I do?

Patch available

Update MCP Atlassian to version 0.22.0

Which compliance frameworks are affected?

Compliance analysis pending. Sign in for full compliance mapping when available.

Frequently Asked Questions

What is CVE-2026-77269?

### Summary The `confluence_upload_attachment` and `confluence_upload_attachments` MCP tools accept a `file_path` parameter and do not validate that the path is confined to an allowed directory before opening the file. An attacker who can call these tools can read any file accessible to the MCP server process (SSH keys, .env files, API credentials) and exfiltrate it by uploading it to Confluence. Note: The Jira `upload_attachment` mixin method in `jira/attachments.py` has the same missing validation, but it is NOT registered as an MCP tool in `servers/jira.py` and is therefore not currently reachable via MCP. It should still be patched to prevent future exposure if Jira upload tools are added. This is an incomplete fix for CVE-2026-27825. That CVE was patched by adding `validate_safe_path()` to download operations (v0.17.0). The same protection was not applied to upload operations. ### Details `validate_safe_path()` is imported in both `confluence/attachments.py` and `jira/attachments.py` and is correctly called in all download functions. It is absent from the Confluence upload functions (which are exposed as MCP tools) and from the Jira upload mixin methods (which are not currently registered as MCP tools but should still be patched). **Download (protected — correctly patched):** ```python # confluence/attachments.py:222-223 validate_safe_path(target_path) # resolves symlinks + checks is_relative_to(cwd) ``` **Upload (vulnerable — not patched):** ```python # confluence/attachments.py:64-79 — NO validate_safe_path() call if not os.path.isabs(file_path): file_path = os.path.abspath(file_path) # normalizes but does NOT restrict # ... files = {"file": (filename, open(file_path, "rb"))} # opens arbitrary file ``` Same pattern in `jira/attachments.py:386`. ### Proof of Concept ```python # Call via MCP client await session.call_tool("confluence_upload_attachment", { "content_id": "12345", "file_path": "/home/user/.ssh/id_rsa" # absolute path — no traversal needed }) # SSH private key is now a Confluence attachment # Retrieve via: confluence_download_attachment or Confluence UI ``` ### Impact Arbitrary file read from the server filesystem. High-value targets: SSH private keys, `.env` files, AWS/GCP credentials, database configuration, source code. ### Fix Add `validate_safe_path(file_path)` call in `confluence/attachments.py:upload_attachment()` (reachable via MCP) and `jira/attachments.py:upload_attachment()` (not currently reachable via MCP, but should be patched preventively), consistent with the existing download protection. No changes to `validate_safe_path()` itself are needed. ```python # Add after os.path.abspath() call: try: validate_safe_path(file_path) except ValueError as e: return {"success": False, "error": str(e)} ```

Is CVE-2026-77269 actively exploited?

No confirmed active exploitation of CVE-2026-77269 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-77269?

Update to patched version: MCP Atlassian 0.22.0.

What is the CVSS score for CVE-2026-77269?

CVE-2026-77269 has a CVSS v3.1 base score of 6.5 (MEDIUM).

What are the technical details?

Original Advisory

### Summary The `confluence_upload_attachment` and `confluence_upload_attachments` MCP tools accept a `file_path` parameter and do not validate that the path is confined to an allowed directory before opening the file. An attacker who can call these tools can read any file accessible to the MCP server process (SSH keys, .env files, API credentials) and exfiltrate it by uploading it to Confluence. Note: The Jira `upload_attachment` mixin method in `jira/attachments.py` has the same missing validation, but it is NOT registered as an MCP tool in `servers/jira.py` and is therefore not currently reachable via MCP. It should still be patched to prevent future exposure if Jira upload tools are added. This is an incomplete fix for CVE-2026-27825. That CVE was patched by adding `validate_safe_path()` to download operations (v0.17.0). The same protection was not applied to upload operations. ### Details `validate_safe_path()` is imported in both `confluence/attachments.py` and `jira/attachments.py` and is correctly called in all download functions. It is absent from the Confluence upload functions (which are exposed as MCP tools) and from the Jira upload mixin methods (which are not currently registered as MCP tools but should still be patched). **Download (protected — correctly patched):** ```python # confluence/attachments.py:222-223 validate_safe_path(target_path) # resolves symlinks + checks is_relative_to(cwd) ``` **Upload (vulnerable — not patched):** ```python # confluence/attachments.py:64-79 — NO validate_safe_path() call if not os.path.isabs(file_path): file_path = os.path.abspath(file_path) # normalizes but does NOT restrict # ... files = {"file": (filename, open(file_path, "rb"))} # opens arbitrary file ``` Same pattern in `jira/attachments.py:386`. ### Proof of Concept ```python # Call via MCP client await session.call_tool("confluence_upload_attachment", { "content_id": "12345", "file_path": "/home/user/.ssh/id_rsa" # absolute path — no traversal needed }) # SSH private key is now a Confluence attachment # Retrieve via: confluence_download_attachment or Confluence UI ``` ### Impact Arbitrary file read from the server filesystem. High-value targets: SSH private keys, `.env` files, AWS/GCP credentials, database configuration, source code. ### Fix Add `validate_safe_path(file_path)` call in `confluence/attachments.py:upload_attachment()` (reachable via MCP) and `jira/attachments.py:upload_attachment()` (not currently reachable via MCP, but should be patched preventively), consistent with the existing download protection. No changes to `validate_safe_path()` itself are needed. ```python # Add after os.path.abspath() call: try: validate_safe_path(file_path) except ValueError as e: return {"success": False, "error": str(e)} ```

Weaknesses (CWE)

CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') Primary CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CWE-22 — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'): The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

[Implementation] Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylis
[Architecture and Design] For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Source: MITRE CWE corpus.