On June 18, 2026, I filed postcss/postcss#2096 about OIDC provenance for PostCSS. The ai
npm account — one person, Andrey Sitnik — publishes PostCSS, nanoid, Autoprefixer, browserslist, and caniuse-lite. Combined: over 900 million weekly downloads through a single publish credential.
Andrey's first reply was not agreement. It was a correction.
From his comment:
Provenance wouldn't save from all of that supply chain attack. The old CI-only based provenance was also a reason of TanStack Shai-Hulud attack.
CI-as-publisher
increasedthe attack risks compared to 2FA manual publishing. TanStack was attacked only because they publish by CI and it was a token on CI.
He is right. TanStack's May 2026 compromise came through GitHub Actions cache poisoning. The attacker got an OIDC token from the CI runner and used it to publish. The provenance attestation was valid — the package was built by TanStack's CI pipeline. The CI pipeline was just also running the attacker's code.
Red Hat's June 1 compromise proved the same pattern. Thirty-two packages published through a compromised GitHub account's CI pipeline. All 32 had valid SLSA provenance attestations.
Andrey's argument: if you publish manually with hardware-bound 2FA (passkey, YubiKey), the attacker needs physical access to your device. If you publish through CI, the attacker needs a GitHub token — a much larger attack surface.
npm's Staged Publishing splits the problem: CI builds and stages. A human approves before latest
moves. A stolen CI token stages a malicious version but never promotes it.
From Andrey's follow-up:
I already moved
nanoid
andnanospy
to the new process, we can test them.PostCSS will be done in a week or two (too many other open source projects) 😅
nanoid's release.yml, updated June 18:
- name: Publish npm package
run: npm stage publish
Andrey said "a week or two." It took nine days. As of June 27, four of the seven packages under the ai
npm account have Staged Publishing enabled:
| Package | Weekly downloads | Staged Publishing | Score |
|---|---|---|---|
| postcss | 251M | ✅ | 85 |
| nanoid | 207M | ✅ | 92 |
| browserslist | 166M | ✅ | 89 |
| autoprefixer | 61M | ✅ | 89 |
| caniuse-lite | 171M | — | 81 |
| postcss-nested | 54M | — | 72 |
| postcss-js | 53M | — | 70 |
That's 685 million weekly downloads now behind a human approval gate. One GitHub issue, nine days, no drama.
Three more packages remain. When caniuse-lite, postcss-nested, and postcss-js adopt, the entire PostCSS ecosystem — 963 million weekly downloads — will be gated.
npx proof-of-commitment
Scans your lockfile. Flags single-publisher packages at scale. Shows provenance, Staged Publishing, and dormant access status. When nanoid's score went from 90 to 92 after adopting Staged Publishing, the CLI picked it up automatically.
The full PostCSS ecosystem audit data comes from Commit, which scores packages on behavioral signals rather than declared metadata.