fix: MCP publish arbitrary file read via spec_path (security) — v0.12.11 - #75
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The readSpecArg function accepted any absolute file path for spec_path without enforcing containment. An MCP client could read any file on the filesystem (e.g. /etc/passwd) by passing its absolute path as spec_path. Fix: added path containment check using isWithinPathResolved. spec_path must be within the workspace .codecarto/ directory or the configured library path. Regression tests verify both rejection and acceptance. 270/270 tests pass (268 + 2 new).
This was referenced Aug 2, 2026
TheAmericanMaker
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Aug 4, 2026
readSpecArg enforced path containment only when allowedRoots was non-empty, and allowedRoots defaulted to []. Containment was therefore opt-in: any caller that omitted the argument would read whatever absolute path the client supplied, reopening the arbitrary-file-read class of bug fixed in v0.12.11 (#75). The only live caller (handlePublish) always passes a non-empty root set, so no released version is exploitable. This closes the gap by construction: - allowedRoots is now a required parameter, so omitting it is a compile error rather than a silent bypass. - An empty root set throws when spec_path is used, instead of skipping the check. - The guard runs before the existence check, so it cannot be used to probe which files exist. - The inline `spec` path is unaffected — it returns before containment. readSpecArg is now exported so the guarantee is directly testable; it is hardened rather than merely private. Four tests added, two of which fail against the previous implementation (verified by reverting). Closes #76 Co-authored-by: James Sesler <James.sesler@pm.me> Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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Security fix
MCP codecarto_publish accepted any absolute file path for spec_path without enforcing containment. An MCP client could read any file on the filesystem by passing its absolute path as spec_path.
Fix
Discovery
Found during the v0.12.9 self-analysis case study security triage. The semantic defect scan (Pass 5: API Contract Violations) identified it. The security triage subagent classified it as blocking.
Validation