vulnerability / NVI-00016450 / Revision 2
MCP Atlassian: Arbitrary file read via confluence_upload_attachment allows exfiltration of server credentials
GitHub lists this reviewed advisory for mcp-atlassian. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.7 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.442%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.38528. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
mcp-atlassian
source listed< 0.22.0
### Summary Missing path validation in `confluence_upload_attachment` allows any authenticated MCP client to read arbitrary files from the server filesystem and exfiltrate their contents to Confluence. On Linux deployments, `/proc/self/environ` yields all runtime secrets in a single call. --- ### Details `AttachmentsMixin.upload_attachment()` in `src/mcp_atlassian/confluence/attachments.py` opens the caller-supplied `file_path` with no boundary check: ```python # line 477 files = {"file": (filename, open(file_path, "rb"))} ``` The download path was correctly hardened in GHSA-xjgw-4wvw-rgm4 via `validate_safe_path()` (lines 223, 272). That fix was not applied to the upload path, leaving it completely unguarded. The MCP tool layer (`servers/confluence.py:1295`) passes `file_path` verbatim with no additional sanitization. --- ### PoC ```bash # 1. Prepare target file (macOS demo; on Linux use /proc/self/environ directly) cp ~/.aws/credentials /tmp/diagram.png # 2. Call the MCP tool confluence_upload_attachment( content_id = "", file_path = "/tmp/diagram.png" ) # 3. Download attachment from Confluence — contains raw credentials ``` Tested on
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-6cr4-ccf3-x7h4 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-77259 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.