Shadow has not had a formal third-party security audit. The v1.1 hardening pass covers resource exhaustion, path traversal, and subprocess injection, but that is not a substitute for a penetration test. If you run Shadow on untrusted inputs in a multi-tenant context, commission an audit.

2.0.0 was a major bump because the shadow.policy_runtime module added new public surface — all 1.x APIs (Session, policy_diff, shadow diff --policy, certificate workflow, .agentlog format) remain backwards compatible at runtime and on the wire. See SPEC.md §13 for .agentlog compatibility guarantees.

Please do not open a public GitHub issue for security problems. A public issue tips off attackers and does not give us time to ship a fix.

Open a private security advisory on the GitHub repo instead. Include:

• A brief description of the vulnerability.
• Steps to reproduce (a minimal repro repo or script if you can).
• The Shadow version or commit SHA and your platform (OS, Rust and Python versions).
• Your expected impact (confidentiality, integrity, availability, supply chain) and severity estimate.

We acknowledge within 72 hours and aim to ship a fix within 30 days for high-severity issues and 90 days for lower severity. We coordinate a disclosure date with you.

• Any code path that handles untrusted .agentlog files. The parser, canonicalization, and content-hashing routines are supply-chain critical.
• The Python SDK's redaction layer. If a default regex misfires and leaks PII or secrets through a reasonable input, that is in scope.
• The shadow CLI invoked from CI or a developer's shell.
• The .github/actions/shadow-action composite action. It writes to PR comments using the caller's github-token.

• Bugs that need the attacker to be the author of the .agentlog file and the consumer's system admin and the Judge. Threat models where the attacker already controls all layers are not interesting.
• Issues in third-party dependencies. Report those upstream. If an upstream CVE lands, file an issue here so we bump the pin.
• Denial of service from a single maliciously crafted trace. A >2^20-iteration bootstrap exhaustion is a known limit. If you find sub-polynomial blow-ups (O(n^3) on n-byte input and similar), please do report.
• The Judge axis behaviour when the user supplies a malicious Judge. The Judge is user code. Treat it like any user-supplied callback.

We default to coordinated disclosure with credit to the reporter (anonymous if you prefer). Once a fix ships, we publish an advisory in CHANGELOG.md under the release header with:

• A description of the vulnerability and impact.
• The fixing commit SHA.
• Credits to the reporter.
• Any user-facing remediation steps.

GitHub's private security advisory channel is the preferred private reporting transport. Access is restricted to the reporter and the repo's security maintainers, and GitHub does not display the advisory publicly until it is published. We do not assert cryptographic end-to-end encryption — GitHub holds the data at rest. If you need a separate cryptographic channel, open the advisory with a note asking for one and we will coordinate a key exchange.

A concrete hardening pass shipped alongside v1.1. Each item names the attack surface, the mitigation, and what is not addressed so you know where your own risk posture has to carry the load.

Risk. A malicious or truncated .agentlog could exhaust memory via a newline-free stream (unbounded read_line), a deeply nested JSON payload, or a multi-gigabyte file.

Hardened.

• DEFAULT_MAX_LINE_BYTES = 16 MiB. Per-line cap enforced via Read::take, so a newline-free stream errors out at the cap rather than growing the buffer.
• DEFAULT_MAX_TOTAL_BYTES = 1 GiB. Whole-trace cap that keeps parse_all from accumulating an unbounded Vec<Record>.
• Both limits are tunable per-Parser via with_max_line_bytes and with_max_total_bytes. Callers ingesting legitimate larger records (multimodal payloads, batch ingest) can raise it.
• New typed errors LineTooLarge { line, bytes, limit } and TraceTooLarge { bytes, limit }. Actionable, not silent.

Not hardened.

• JSON depth limits beyond serde_json's default recursion guard. Out of scope for a local-first tool. For server-side ingestion, wrap the parser in your own JSON sanity layer.

Risk. SHADOW_SESSION_OUTPUT lets the shim write wherever the invoking user can. A poisoned shell profile could redirect output somewhere unwanted.

Hardened.

• shadow record writability-preflights the output path in the parent before spawning the child. Test-locked via test_shadow_record_fails_fast_on_unwritable_output_path.
• Env handling: no user-input splat. Only SHADOW_SESSION_OUTPUT, SHADOW_SESSION_TAGS, and an augmented PYTHONPATH are set.

Not hardened.

• The shim does not verify the output path is inside the caller's project dir. Same posture as any env-var-driven test runner.

Risk. Path traversal via ../../../etc/ style arguments. Always scoped to what the invoking user can write, so low impact, but bad form and worth closing.

Hardened.

• Both commands use Path.resolve() before any write. Symlink tricks resolve before the write check. Writes to paths outside the current working directory fail cleanly.

Not hardened.

• We do not disallow absolute paths outright. Users legitimately want to scaffold into ~/projects/foo/.

Not a real risk. subprocess.run(args, shell=False, env=env) is the only spawn path. No shell-string concatenation. The user's argv is passed verbatim as an argument vector. Documented for reviewers who want to confirm by inspection.

Hardened.

• Every wheel on PyPI is signed via Sigstore cosign (keyless OIDC). Attestations published alongside the GitHub Release.
• CycloneDX 1.5 SBOMs attached to each release (Python, Rust, and TypeScript components).
• PyPI uploads use Trusted Publisher (OIDC). No long-lived token stored anywhere.

Not hardened.

• We do not ship reproducible builds. Two consecutive maturin build invocations on the same commit produce byte-identical wheels on the same machine, but not necessarily across machines.

If you find something this pass missed, please open a private security advisory as described above. Anything reported in good faith will be credited (or kept anonymous at your preference) in the release notes when the fix ships.