CVE-2026-77269

mediumpriority · track · 0EPSS 0.004 · 37 %ileUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.43% (37th) EPSS
CVSS 6.5 · medium
Is it mine?
2 products
Check your exposure
Who says so?
2 sources
osv · nvd

EPSS · scored 2026-10-27

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the remediation for CVE-2026-27825 protects download destinations but does not constrain source paths used by attachment uploads. A caller can provide an absolute or traversal file_path and cause the server to upload the selected local file. The advisory traces the vulnerable input and processing flow through upload_attachment, file_path, and CVE-2026-27825, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

01

cvss

Technical severity, 0–10. One row per scoring source.

6.5
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · security-advisories@github.comexploitability 2.8 · impact 3.6
v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · OSV
v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

04

affected products (2)

Products and version ranges known to be affected.

05

advisories (2)

Vendor and ecosystem advisories describing this.

  • GHSA-h7wj-5v37-59r2MCP Atlassian: Path traversal in upload_attachment allows arbitrary file read (incomplete fix for CVE-2026-27825)2026-09-22ghsa · osvUS

    ### 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)} ```

  • PYSEC-2026-4095MCP Atlassian: Path traversal in upload_attachment allows arbitrary file read (incomplete fix for CVE-2026-27825)2026-10-01vendor · osvUS

    ### 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)} ```

06

also known as (2)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

published 2026-09-22modified 2026-09-29
08

references (4) nvd

External citations — patches, advisories, analysis.

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