[rudycelekli]

Bug

mcpproxy catalog search and mcpproxy catalog show print registry-supplied strings (title, id, publisher, description, install command, required input names) straight to the terminal. The search table only byte-truncates the title, and show prints everything with %s.

These strings come from remote registries (the official registry, Smithery, custom registries entries). An entry whose title or description contains ANSI escapes can clear or rewrite the operator's screen. A newline can forge extra table rows next to a real result, for example a fake ✓ added line.

mcpproxy tools list already escapes upstream-controlled text for this reason, using sanitizeCell/sanitizeDescriptionCell and detect.CapEvidence (GH #938). The catalog commands never got the same treatment.

Trigger

A registry entry with this title:

"\x1b[2J\x1b[1;1HTotally Safe\nofficial  trusted  http  ✓"

Running mcpproxy catalog search <q> or mcpproxy catalog show official/<id> writes the raw ESC sequences to the tty.

Fix

Run the registry-supplied fields through the existing helpers:

• sanitizeDescriptionCell for prose (the title, which keeps the 40-rune cap, and the description).
• sanitizeCell for identifiers (id, publisher, transport, install URL and command, input names).

Control and format runes are escaped (made visible), not dropped. JSON/YAML output is unchanged.

Test

TestCatalogOutput_EscapesRegistryControlCharacters renders a poisoned result through printCatalogTable and renderCatalogShow and asserts that neither output contains a raw ESC byte.

Commands run

• go vet ./cmd/mcpproxy: clean
• go test -count=1 ./cmd/mcpproxy: ok (cgo build, run locally with SDKROOT set to the macOS 26.5 SDK)
• With the fix reverted (git stash of catalog_cmd.go), the new test fails with search table wrote a raw ESC to the terminal and show wrote a raw ESC to the terminal.
• gofmt -l on the edited files: no output

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/mcpproxy/catalog_cmd.go	96.87%	1 Missing ⚠️

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[Dumbris]

Verified the bug on main and the fix; thank you! The review found one gap, so I pushed a small maintainer commit on top of your branch: sanitizeCell(s, 0) still caps at 200 runes via detect.CapEvidence, so catalog show/search cut the ID (which catalog add must match exactly) and could hide the tail of an install command. The commit escapes control and format runes without truncating (the table title keeps its 40-char cap) and adds TestCatalogOutput_EscapingDoesNotTruncate.

I will merge once CI is green.

[Dumbris]

Verified: the bug reproduces on main and the PR fixes it. The review found one gap, closed by the maintainer commit on top (regression test included). Race tests and CI lint for the touched packages are clean on this branch merged with main, and the result was cross-reviewed clean.

[rudycelekli]

The remaining binary-build failure on current head dc9eb71fc86bd554269af005654e2f7fa2bdeba2 is in macOS DMG packaging: hdiutil: create failed - Resource busy in create-app-dmg.sh, after the Go core and Swift app bundle were built. The matrix then cancelled the sibling binary jobs.

Failed macOS arm64 job. I attempted to rerun the failed jobs, but GitHub denied the request (Must have admin rights to Repository). A maintainer rerun is needed to determine whether the runner resource error clears; no source change appears justified by this log.

[Dumbris]

Merged. Thank you, @rudycelekli! catalog search and catalog show now escape registry-supplied text, so a malicious registry entry can no longer inject terminal escape sequences into the CLI output, and IDs stay intact for copy-paste.

Contributions like this are what keep MCPProxy moving, and they matter a lot to the project.

One small ask, only if you feel like it: a short public note about your change (a tweet, a LinkedIn post, a line in a community you are part of) helps more people discover MCPProxy. No pressure at all, and I would be glad to repost it.