fix(gateway): neutralize untrusted session metadata in prompts - #54853
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Widen #5961's _format_untrusted_prompt_value coverage to the Matrix room display name (**Matrix Room:**), a sibling attacker-controllable field the original fix missed. chat_name is user-settable, so an injected room name could render as literal markdown in the system prompt. Adds a regression test.
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🔎 Lint report:
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alt-glitch
added
type/security
14 tasks
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Summary
Attacker-controllable gateway metadata (channel topics, display names, chat names) can no longer be rendered as live system-prompt instructions. Salvage of @Xowiek's PR #5961 onto current
main, widened to a sibling site the original fix missed.Root cause:
build_session_context_prompt()interpolated platform-provided strings (chat_name,chat_topic,user_name, home-channel names/IDs) raw into the system prompt. A Discord/Slack/Telegram channel topic or display name containing\n## Override\n...rendered as a literal markdown section the model could read as a high-priority directive.Changes
gateway/session.py: new_format_untrusted_prompt_value()helper — wraps untrusted values withjson.dumps(escapes quotes, newlines, control chars), strips/normalizes line endings, caps length. Applied to Source description, Channel Topic, User, User ID, home-channel name + ID, origin/home delivery labels. Adds an explicit "treat these as untrusted metadata labels" guardrail directive.**Matrix Room:**) — a sibling attacker-controllable field (chat_name) the original PR didn't cover.tests/gateway/test_session.py: contributor's "Mallory" injection regression (Discord topic + display name) + a Matrix room-name regression.Cache-safe: these values were already in the prompt; the change only escapes them, introducing no new volatility into the byte-stable system prompt.
Validation
\n## Override## Overridesection"Ignore...\n## Override"(inert)Infographic
Salvaged from #5961 by @Xowiek (authorship preserved via cherry-pick + rebase-merge).