fix(security): harden web_fetch SSRF checks and rustls TLS - #187
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Reject non-http(s) schemes, abbreviated/decimal IPv4 loopback, IPv6-mapped addresses, CGNAT, unique-local IPv6, and DNS-resolved private targets. Bound marketplace fetch timeouts/redirects. Enable rustls on the providers feature, bump rustls past RUSTSEC-2026-0285, allow CDLA-Permissive-2.0 for webpki-roots, and run cargo-deny in CI. Amp-Thread-ID: https://ampcode.com/threads/T-01a0a5f1-67fb-76fe-ac75-eae1b8f3a08a Co-authored-by: Max Carter <undivisible@vk.com>
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Why
web_fetchSSRF validation was host-string matching only: it missedfile://, decimal/abbreviated IPv4 (2130706433,127.1), IPv6-mapped loopback, CGNAT, unique-local IPv6, DNS rebinding, and open redirects. Theprovidersfeature also enabled reqwest withdefault-features = falseand no TLS backend.What
http/https) and real IP classification before fetch.providersnow enablesreqwest/json+reqwest/rustls-tls.deny.toml: CDLA-Permissive-2.0; ignore unmaintained bincode viafff-search.cargo deny check.Tests
cargo test --no-default-features --features providers,builtin-tools,mcp --lib— 513 passedcargo clippy --no-default-features --features providers,builtin-tools,mcp,ipc,marketplace --lib -- -D warningscargo deny check— advisories/bans/licenses/sources okNot merged: security-sensitive; needs review.
Note
High Risk
Security-critical changes to agent network fetch paths, TLS for providers, and redirect/DNS behavior; misclassification could block legitimate URLs or leave SSRF gaps.
Overview
Hardens
web_fetchagainst SSRF:http/httpsonly, stricter host/IP blocking (decimal/abbreviated IPv4, IPv6-mapped loopback, CGNAT, unique-local), DNS resolution checks for hostnames, and a dedicated reqwest client (30s timeout, max 5 redirects) that rejects redirects to blocked targets instead of using the provider global client.The
providersfeature now wiresreqwestwith rustls TLS (reqwest/json,reqwest/rustls-tls);Cargo.lockbumps rustls. Marketplace index fetch gets the same 30s timeout and 5-redirect cap. CI runscargo deny check;deny.tomladds CDLA-Permissive-2.0, workspace-level unmaintained handling, and yanked = warn. Provider HTTP client build usesexpectinstead of falling back to a default client on failure. Unit tests cover URL validation and destination checks.Reviewed by Cursor Bugbot for commit 783f531. Configure here.