vulnerability / NVI-00013969 / Revision 1
MCP Atlassian: OAuth fallback token storage writes plaintext access and refresh tokens with group-readable permissions
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.
6.1 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
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 When OAuth tokens are saved, MCP Atlassian always writes a plaintext fallback copy under `~/.mcp-atlassian/oauth-.json`. The fallback file is created with the process default umask rather than restrictive permissions. In this environment the file was created as mode `0664`, exposing access and refresh tokens to same-group local users and any process that can read the home directory. ### Details `OAuthConfig._save_tokens()` stores OAuth token data in keyring, but it also unconditionally maintains a plaintext file fallback for backwards compatibility in `src/mcp_atlassian/utils/oauth.py:350-386`. If keyring saving fails it also falls back to the same file path in `src/mcp_atlassian/utils/oauth.py:387-391`. The fallback writer creates `~/.mcp-atlassian` and then writes `oauth-.json` with a normal `open(token_path, "w")` call in `src/mcp_atlassian/utils/oauth.py:392-420`. No `mode=0o600`, `os.open(..., 0o600)`, `chmod`, or owner-only directory permission is applied. The file contains both `access_token` and `refresh_token` (`src/mcp_atlassian/utils/oauth.py:360-367`) and is later loaded from the same plaintext path in `src/mcp_atlassian/utils/oauth
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. GitHub Advisory Database
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-g5xv-mhgm-v5f6 ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
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