critical severityConfidence highHistorical record

Fastify malformed URLs can skip not-found auth

Direct answer

Fastify malformed URLs can skip not-found auth, also tracked as CVE-2026-76169 / fastify malformed URL auth bypass is a critical-severity threat campaign HOL Guard tracked from Sep 4, 2026 to Sep 4, 2026, verified against 3 primary sources and last reviewed Sep 20, 2026. Active tracking has ended and the record remains published as a permanent historical research record.

Fastify before 5.12.2 can let malformed URLs reach encapsulated not-found handlers and skip intended authentication. Upgrade to 5.12.2.

Also tracked as CVE-2026-76169 · fastify malformed URL auth bypass

First observed
Sep 4, 2026
Last observed
Sep 4, 2026
Last reviewed
Sep 20, 2026
Tracking ended
Sep 4, 2026

Record exports

JSON recordArtifact CSVSTIX 2.1 bundle

Uncertainty and limitations

Read the evidence limits before acting on this record.

Confirm your Fastify major and encapsulation/auth pattern before treating risk as universal.

  • Scoped to not-found / encapsulation auth patterns.
  • Fixed version 5.12.2 from GHSA.
  • HOL blog is operator guidance.

Guard coverage and policy

What Guard's reviewed assertions do and do not claim for this campaign, and the reviewed starting points for defense.

No Guard coverage mapping or campaign-specific policy guidance is published for this record.

Safe next step. Campaign guidance is defensive context. It does not auto-apply policy or claim universal campaign coverage.

Open policy controlsCampaign-specific emergency policy starting point

Timeline

Reviewed events, oldest first, each tied to a verified source.

  1. Disclosure

    CVE-2026-76169 Fastify malformed URL not-found auth bypass disclosed.

    Sources:GitHub Security Advisory GHSA-p68q-wchp-6fh7·NVD CVE-2026-76169

  2. Update

    HOL Guard published operator coverage for CVE-2026-76169.

    Source:HOL Guard operator write-up

Publication clock: 404.1 hours from reviewed disclosure timestamp to HOL publication; 12-hour critical target; historical backfill outside target.

Reviewed artifacts

The specific artifacts this record concerns, as reviewed. Names and versions are shown as text; a registry link is not recorded here.

  • fastify@>=4.0.0 <5.12.2npmpackage

Sources

Every claim on this record is traceable to the sources below.

Campaign questions, answered

Fastify before 2 can let malformed URLs reach encapsulated not-found handlers and skip intended authentication. HOL Guard tracked the campaign from Sep 4, 2026 to Sep 4, 2026.

No. Active tracking ended Sep 4, 2026; this page remains as a labeled historical research record and does not imply the threat is currently active.

The record cites 3 primary sources, names 1 reviewed artifact, and was last fully reviewed Sep 20, 2026 by HOL Guard Security Publishing. Its uncertainty and limitations are stated on the record itself.

Campaign guidance is defensive context. It does not auto-apply policy or claim universal campaign coverage.

The permalink above is permanent. The full record can be downloaded from this page as JSON, an artifact CSV, and a STIX 2.1 bundle, and corrections can be requested through the published correction path on the record. Confirm your Fastify major and encapsulation/auth pattern before treating risk as universal.

Reviewed in full by HOL Guard Security Publishing.

Published
Last full review
Last modified

Report a correction

Record HGTC-2026-9574024A