Only the latest tagged release and main receive security fixes. Release candidates (-rcN) are supported until the corresponding final release ships.

Report suspected vulnerabilities privately via GitHub Security Advisories:

https://github.com/srdjan/zigttp/security/advisories/new

Do not open public issues for security reports. After triage you will receive a remediation plan or a rationale for closing the report.

Include, where possible:

• Affected version (tag, commit, or binary hash)
• Minimal reproducer (handler source, CLI flags, request)
• Observed vs. expected behavior
• Impact assessment (panic, isolation bypass, data exposure, etc.)

In scope: the runtime (packages/runtime/), the zigts engine and virtual modules (packages/zigts/), the build-time tooling (packages/tools/), and the zigttp deploy client path.

Out of scope: the hosted control plane itself (api.zigttp.dev), which has its own reporting channel, and third-party extensions built with zigttp-sdk.

The high-level boundaries enforced by zigttp:

1. Handler isolation. Each request acquires a Runtime instance from a pool. Recycling under reuse_unbounded is only enabled when the compile-time contract proves pure + deterministic. Arena-escape and string-table audits run on every release; failures are logged via the runtime metrics (arena_audit_failures, persistent_escape_failures).

2. Capability boundary. Virtual modules declare required_capabilities in their ModuleBinding. The set is aggregated into the handler's contract and used by deployment policy to refuse mounts that exceed the granted surface. See docs/internals/capability-audit.md for the per-module review and known caveats (only .runtime_callback is enforced at module call time; other capabilities are policy-level).

3. HTTP boundary. Headers reject CRLF and NUL bytes before allocation (commit 6e65bb7, packages/runtime/src/http_types.zig). Body size defaults to 1 MiB and is rejected with 413 on overflow. Static-file paths reject traversal (..), absolute paths, drive letters, and NUL bytes (isPathSafe); a second-line canonical-realpath check (isCanonicalPathInsideRoot) catches symlink escapes.

4. WebSocket boundary. RFC 6455 frame parsing is delegated to std.http.Server.WebSocket; runtime maps stdlib errors to wire-correct close codes (1002 for protocol error, 1009 for oversize). See docs/internals/websocket-audit.md for the full checklist and the one documented gap (peer-sent close-code validation, deferred to W2).

5. Attestation trust model. Slice 1 (current beta): the JWS protected header carries the full Ed25519 public key. zigttp verify <url> validates the signature against that embedded key and prints the key fingerprint. This proves "the holder of this key signed these claims" - not "this key belongs to a specific publisher." For now, third-party verifiers should pin keys with --trust-key <hex>. Slice 2 adds identity binding via well-known endpoints. See docs/roadmap/attest-slice-1.md and docs/roadmap/attest-slice-2.md.

6. Self-extracting binary integrity. The 32-byte trailer's CRC-32 is a corruption check, not a security check. The actual integrity boundary is the JWS attestation over (bytecode_sha256, contract_sha256, policy_sha256). See docs/internals/architecture.md - Self-Extracting Binary Trailer.

7. Bytecode integrity. Only bytecode that passes packages/zigts/src/bytecode_verifier.zig is dispatched into the VM. The verifier validates opcodes, operand bounds, the constant pool, stack discipline, and jump targets before the first instruction executes. Untrusted bytecode (e.g. a tampered self-extracting payload) is rejected before bytecode execution.

8. No runtime multipart parser. multipart/form-data request bodies are passed to the handler unparsed. Handlers must parse boundaries themselves and reject malformed inputs; the runtime guarantees only Content-Length and total-body-size enforcement (default 1 MiB). Treat handler-side multipart parsing as untrusted-input handling.

• docs/threat-model.md - public runtime and tooling threat model
• docs/verification.md - compile-time verification invariants
• docs/internals/capability-audit.md - per-module capability declaration audit
• docs/internals/websocket-audit.md - RFC 6455 compliance audit
• packages/zigts/src/module_binding.zig - capability enforcement surface
• docs/design/zigttp_zigts_policy_wasm_spec.md - deferred Wasm policy runtime design