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Fencer Intel
high 8.1

CVE-2026-92087 json

@fastify/auth vulnerable to Authorization Bypass via order-dependent evaluation of composed auth

published last mo. modified last mo. also EUVD-2026-80788 , GHSA-7h52-2rwr-m76r

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository fastify/fastify-auth. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

@fastify/auth is a Fastify plugin that composes multiple authentication and authorization strategies into a single route guard. In versions 5.0.0 through 5.1.0, when strategies are composed with the relation "or" option together with the run "all" option and one entry is a nested array acting as an AND group, the group is evaluated in an order-dependent way: an earlier failing check is silently dropped and the group's result becomes the outcome of its last check. As a result, a request that satisfies only the last member of an AND group, for example an attacker who holds a valid API key but is not an administrator, is authorized instead of rejected, and a related order-dependent bypass affects the mirror configuration where the top-level relation is "and" and a nested group uses "or". The issue is fixed in @fastify/auth 5.1.1, and users should upgrade to 5.1.1 or later. As a workaround, omit the run "all" option where it is not required, order each AND group so its stricter check is evaluated last, or replace nested AND groups with an explicit top-level "and" composition.

Patch / fix

  • npm @fastify/auth 5.1.1
  • @fastify/auth @fastify/auth 5.1.1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-92087 updated cvss 8.1

@fastify/auth: @fastify/auth: Authorization Bypass via order-dependent authentication evaluation

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
last mo.

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm @fastify/auth
>=5.0.0, <5.1.1
5.1.1

Affected products

  • @fastify/auth @fastify/auth

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of fastify/fastify-auth published their own advisory on GitHub. Reviewed sources take precedence over it.