fix(mcp): bound unbounded regex cache in name_referenced_in - #6296
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July 14, 2026 19:28
name_referenced_in memoized a compiled Regex per distinct lowercased MCP tool name in two process-lifetime static HashMap caches with no eviction. Tool names are attacker-influenced (untrusted MCP server input), so a malicious or reconnecting server rotating its advertised tool names could grow both caches without bound, leaking memory over the lifetime of a long-running daemon/gateway/serve process. Replace both caches with lru::LruCache capped at 256 entries, using get_or_insert as a drop-in replacement for entry().or_insert_with() with the same single-lock-acquisition semantics. Add a regression test that churns well past the cap and confirms a long-evicted entry still matches correctly on recompile. Closes #6255
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Summary
name_referenced_inincrates/zeph-mcp/src/sanitize.rsmemoized a compiledRegexper distinct lowercased MCP tool name in two process-lifetime static caches with no eviction; since tool names are attacker-influenced (untrusted MCP server input), a malicious or reconnecting server rotating its advertised tool names could grow both caches without bound, leaking memory over the lifetime of a long-running daemon/gateway/serve process.HashMap<String, Regex>caches withlru::LruCache<String, Regex>capped at 256 entries (NAME_REGEX_CACHE_CAPACITY), usingget_or_insertas a drop-in replacement forentry().or_insert_with()with the same single-lock-acquisition semantics — no new attack surface, no TOCTOU.lruwas already a workspace dependency (0.18.0, used identically incrates/zeph-memory/src/graph/ontology.rs), so this addslru.workspace = truetocrates/zeph-mcp/Cargo.tomlwith no new crate/version.name_referenced_in_cache_bounded_survives_churn) that churns well past the cap on both cache branches and confirms a long-evicted entry still matches correctly on recompile.Closes #6255
Test plan
cargo +nightly fmt --checkcargo clippy --profile ci --workspace --all-targets --features "desktop,ide,server,chat,pdf,scheduler,testing" -- -D warningscargo nextest run --config-file .github/nextest.toml --workspace --features "desktop,ide,server,chat,pdf,scheduler" --lib --bins(13694 passed, 0 failed, 34 skipped)RUSTFLAGS="-D warnings" RUSTDOCFLAGS="--deny rustdoc::broken_intra_doc_links" cargo doc --no-deps --workspace --features "desktop,ide,server,chat,pdf,scheduler"gitleaks protect --staged --no-banner --redact