b8fc2e9e33
scan_sbom.py reported 50 advisory matches against shipped components, 16 of them at or above HIGH. This clears all of them: the scan now reports 0 shipped findings and the gate passes. pyjwt 2.12.1 -> 2.13.0 idna 3.13 -> 3.19 axios 1.13.2 -> 1.20.0 (29 advisories) postcss 8.5.6 -> 8.5.26 dompurify 3.4.11 -> 3.4.14 nanoid 3.3.11 -> 3.3.18 follow-redirects 1.15.11 -> 1.16.0 form-data 4.0.5 -> 4.0.6 Every one is an in-major bump inside a range the manifests already allowed, so this is a lockfile refresh rather than a migration. The Python side was compiled with --upgrade-package for each name so nothing else moved; the diff is two version lines and their hashes. nanoid is worth recording: it is transitive under postcss at ^3.3.11, and its advisories are fixed on both the 3.x and 5.x branches. 3.3.18 is the fix that is actually reachable. The declared floors for axios and dompurify were raised to the versions in the lockfile. They were ^1.6.0 and ^3.4.11, which still nominally admitted the vulnerable range - npm resolves to the highest match so an install was never going to pick one, but the manifest should state the minimum safe version rather than rely on that. axios 1.20 adds optional proxy-agent support, which pulls https-proxy-agent and agent-base into the tree. Both are Node-only and neither reaches the browser bundle; the build was checked for them. The main chunk grew 256kB to 271kB (85.7kB to 90.5kB gzipped) from the rest of the axios delta. The PyJWT entry in the allowlist was removed rather than kept. It stopped matching the moment the upgrade landed, and an allowlist that accumulates entries for advisories that no longer apply is one nobody rereads. The reasoning is preserved as the worked example in docs/DEPENDENCY-SECURITY.md. Verified: full suite 2161 passed, frontend 273 passed, build clean, npm audit --omit=dev reports 0 vulnerabilities.
101 lines
4.6 KiB
Markdown
101 lines
4.6 KiB
Markdown
# Dependency security
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Two scripts, one question each.
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| question | script | output |
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| what are we running | `scripts/generate_sbom.py` | `sbom.cdx.json`, CycloneDX 1.6, shipped with every release |
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| are we exposed | `scripts/scan_sbom.py` | a report, and an exit code |
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The SBOM was already generated and installed onto every server. Nothing read
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it, so "are we exposed to this advisory" was still a person going and looking.
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The scanner closes that.
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## Running it
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```bash
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venv/bin/python scripts/scan_sbom.py # report, exit 0
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venv/bin/python scripts/scan_sbom.py --gate # exit 1 on a shipped finding
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venv/bin/python scripts/scan_sbom.py --json out.json # machine-readable too
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```
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With no `--sbom`, it generates one first, so there is never a stale input.
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It needs outbound HTTPS to `api.osv.dev`. **Run it where the repository lives,
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not on a customer's server** - a deployed instance is frequently air-gapped and
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has nothing to query. That is also why the SBOM ships as a file: it is the
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artefact a security team scans on their own terms.
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## Why OSV
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It takes a purl and returns the advisories that apply. No account, no API key,
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no agent installed anywhere, no vulnerability database to keep current. The
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SBOM is already the input it wants, so this is a lookup against what shipped
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rather than a second scan of the tree that could disagree with it.
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## Shipped and build-only are not the same finding
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Two thirds of the components in the SBOM are build tooling - bundlers, test
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runners, their transitive dependencies. They never reach a server, and the SBOM
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already marks them `scope: excluded`.
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Both are reported. **Only shipped components can fail a build.**
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This is deliberate. At the time of writing, the highest-severity match in the
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whole tree is a CRITICAL against the test runner, which is not installed
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anywhere a release reaches. A gate that fails on that teaches everybody to pass
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`--no-verify` within a month, and then it catches nothing at all.
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## Severity is taken, not computed
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Where an advisory records a plain word - GHSA gives LOW, MODERATE, HIGH,
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CRITICAL - that word is used. Where there is only a CVSS vector, the report says
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UNKNOWN rather than parsing the vector into a score it might get wrong.
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UNKNOWN is shown and never gates. A guessed score is worse than an honest gap,
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because somebody would act on it.
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## The allowlist is a record, not a mute button
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`scripts/vulnerability-allowlist.json` holds advisories that were reviewed and
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accepted. An entry carries the advisory id, the reason, who accepted it, the
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date, and what would invalidate the reasoning.
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A good reason names the precondition that is absent. The file has held exactly
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one entry so far, and how it ended is the point.
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A PyJWT advisory rated HIGH - algorithm confusion, forged HS256 tokens - needs a
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verifier configured with both symmetric and asymmetric algorithms AND a raw JSON
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JWK passed as the key. This application configures neither: there is no
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`JWT_ALGORITHM` or `JWT_DECODE_ALGORITHMS` anywhere in the tree, so
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flask-jwt-extended runs HS256-only against a string secret. That was written
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down, with `invalidatedby` recording what would make it untrue - SSO issuing
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tokens verified against a JWK.
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Then PyJWT was upgraded, the advisory stopped matching, and the entry was
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deleted. The allowlist is empty again, which is the state to aim for.
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`invalidatedby` is the field that earns its keep. A reason stops being true when
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the code that made it true changes, and nobody re-reads an allowlist looking for
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that. Write down what would break it.
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Upgrading is almost always cheaper than defending a decision to skip it. Do not
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add an entry to make a build pass.
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## What the report tells you to do
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The report ends with a per-component upgrade rollup: the smallest upgrade that
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clears every advisory against that component, and how many it clears.
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"Smallest" is doing real work there. An advisory patched on several release
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branches lists a fix per branch - nanoid's is fixed in both 3.3.18 and 5.1.16 -
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and taking the highest recommends a major upgrade when a patch on the current
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branch would do. Where the package is transitive that major may not even be
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reachable: nanoid arrives under postcss, pinned `^3.3.11`, a range 5.x cannot
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satisfy. So the target is the lowest published fix above the version in use.
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Fixes on older branches are ignored rather than offered as a downgrade.
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A target on a different major version is still labelled `MAJOR`, but now that
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label means something: no fix exists on the current branch, so the upgrade is
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genuinely a different job - it can be ESM-only, or drop an API.
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