[FIX][PLUGINS]: Fix X-Vault-Token header leaking to MCP servers on misconfiguration#3033
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crivetimihai merged 3 commits intoIBM:mainfrom Feb 20, 2026
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crivetimihai
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Good security fix. The X-Vault-Tokens header was leaking to the upstream MCP server in three cases:
- JSON parse error — returned
ToolPreInvokeResult()without removing the header - No token match — returned
ToolPreInvokeResult()without removing the header - Only removed on
if modified— missed the case where processing happened but no auth header was added
Moving the del headers[vault_header_name] immediately after parsing (and also in the error path) ensures the header is always stripped regardless of downstream logic. Tests correctly verify removal in both error and no-match scenarios.
Signed-off-by: popagruia <adrian.popa@ro.ibm.com>
…d validate parsed token type - Strip vault header even when system cannot be determined from gateway metadata - Validate that parsed vault tokens are a JSON object (dict), not array/string/etc. - Remove misleading type annotation on orjson.loads result - Update test to verify header stripping on missing system tag Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>
Add two new test cases: - test_no_system_tag_no_vault_header_returns_empty: covers the branch where system key cannot be determined and no vault header is present - test_non_dict_json_vault_tokens_stripped: covers the isinstance guard ensuring non-dict JSON (e.g. arrays) strips the vault header without injecting auth headers Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>
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@popagruia — please review the changes and let me know if anything looks off. |
vishu-bh
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Feb 24, 2026
…sconfiguration (#3033) * x-vault-tokens is not propagated even if the system is misscomfigured Signed-off-by: popagruia <adrian.popa@ro.ibm.com> * fix(vault): strip X-Vault-Tokens header when system tag is missing and validate parsed token type - Strip vault header even when system cannot be determined from gateway metadata - Validate that parsed vault tokens are a JSON object (dict), not array/string/etc. - Remove misleading type annotation on orjson.loads result - Update test to verify header stripping on missing system tag Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * test: add coverage for no-system-tag and non-dict vault tokens paths Add two new test cases: - test_no_system_tag_no_vault_header_returns_empty: covers the branch where system key cannot be determined and no vault header is present - test_non_dict_json_vault_tokens_stripped: covers the isinstance guard ensuring non-dict JSON (e.g. arrays) strips the vault header without injecting auth headers Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> --------- Signed-off-by: popagruia <adrian.popa@ro.ibm.com> Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> Co-authored-by: popagruia <adrian.popa@ro.ibm.com> Co-authored-by: Mihai Criveti <crivetimihai@gmail.com>
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📝 Summary
Security fix for vault_plugin. When a MCP server is added with header passthrough for X-Vault-Tokens but system tag is none or missing the X-Vault-Tokens is send to server.
🏷️ Type of Change
🧪 Verification
make lintmake testmake coverage✅ Checklist
make black isort pre-commit)