fastify vulnerable to header validation bypass via incomplete schema case normalization
Exploitation and risk
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cve-program · CVE-2026-84428
Publishedfastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later.
- Source published
- 4 Sep 2026 10:24:27 UTC
- Source modified
- 4 Sep 2026 16:06:04 UTC
- Saved here
- 23 Oct 2026 15:48:27 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
euvd · EUVD-2026-70998
Publishedfastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later.
Additional publisher context
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Sep 4, 2026, 10:24:27 AM
dateUpdated: Sep 4, 2026, 4:06:04 PM
3 related source bulletins · separate from aliases
RHSA-2026:90321: Red Hat Security Advisory: Red Hat OpenShift Dev Spaces 3.31.0 Release.
CVE-2023-54404 · CVE-2025-62718 · CVE-2026-8643 · CVE-2026-9496 · CVE-2026-12185 · CVE-2026-13697 · CVE-2026-14682 · CVE-2026-15076 · CVE-2026-16308 · CVE-2026-17106 · CVE-2026-18427 · CVE-2026-19203 · CVE-2026-19534 · CVE-2026-39820 · CVE-2026-41178 · CVE-2026-41707 · CVE-2026-42499 · CVE-2026-42502 · CVE-2026-45416 · CVE-2026-47884 · CVE-2026-47886 · CVE-2026-47888 · CVE-2026-47890 · CVE-2026-47892 · CVE-2026-50010 · CVE-2026-55831 · CVE-2026-55833 · CVE-2026-55851 · CVE-2026-56745 · CVE-2026-56746 · CVE-2026-56819 · CVE-2026-56852 · CVE-2026-56854 · CVE-2026-58062 · CVE-2026-59280 · CVE-2026-59282 · CVE-2026-59283 · CVE-2026-59296 · CVE-2026-59313 · CVE-2026-59323 · CVE-2026-59651 · CVE-2026-59887 · CVE-2026-59899 · CVE-2026-59901 · CVE-2026-62243 · CVE-2026-64607 · CVE-2026-67213 · CVE-2026-67312 · CVE-2026-67313 · CVE-2026-67314 · CVE-2026-67320 · CVE-2026-67321 · CVE-2026-68494 · CVE-2026-68497 · CVE-2026-69152 · CVE-2026-69192 · CVE-2026-71290 · CVE-2026-71324 · CVE-2026-71325 · CVE-2026-71327 · CVE-2026-73500 · CVE-2026-73508 · CVE-2026-74835 · CVE-2026-75838 · CVE-2026-75899 · CVE-2026-75931 · CVE-2026-76169 · CVE-2026-81521 · CVE-2026-82417 · CVE-2026-82562 · CVE-2026-84292 · CVE-2026-84375 · CVE-2026-84394 · CVE-2026-84428 · CVE-2026-84445 · CVE-2026-84469 · CVE-2026-84504 · CVE-2026-84961 · CVE-2026-85062 · CVE-2026-85124 · CVE-2026-85152 · CVE-2026-85595 · CVE-2026-85597 · CVE-2026-86063 · CVE-2026-87743 · CVE-2026-88004 · CVE-2026-88007 · CVE-2026-88008 · CVE-2026-88009 · CVE-2026-88011 · CVE-2026-88012 · CVE-2026-88031 · CVE-2026-88878 · CVE-2026-88879 · CVE-2026-90711 · CVE-2026-93749 · CVE-2026-100655 · CVE-2026-100656 · CVE-2026-100666 · CVE-2026-101916 · CVE-2026-102925 · CVE-2026-102930 · CVE-2026-103435 · CVE-2026-109618 · CVE-2026-109619
RHSA-2026:87410: Red Hat Security Advisory: RHOAI 2.25.12 - Red Hat OpenShift AI
CVE-2024-12224 · CVE-2025-14920 · CVE-2025-14921 · CVE-2025-14924 · CVE-2025-14925 · CVE-2025-14926 · CVE-2025-14927 · CVE-2025-14928 · CVE-2025-14929 · CVE-2025-14930 · CVE-2025-61726 · CVE-2025-61729 · CVE-2026-5241 · CVE-2026-5497 · CVE-2026-6734 · CVE-2026-8643 · CVE-2026-9697 · CVE-2026-11822 · CVE-2026-11824 · CVE-2026-12151 · CVE-2026-12860 · CVE-2026-15143 · CVE-2026-15574 · CVE-2026-15679 · CVE-2026-15925 · CVE-2026-16221 · CVE-2026-18427 · CVE-2026-18446 · CVE-2026-18949 · CVE-2026-19481 · CVE-2026-19484 · CVE-2026-19534 · CVE-2026-25681 · CVE-2026-25960 · CVE-2026-27136 · CVE-2026-28390 · CVE-2026-28684 · CVE-2026-31812 · CVE-2026-32283 · CVE-2026-33186 · CVE-2026-33805 · CVE-2026-33811 · CVE-2026-33814 · CVE-2026-34993 · CVE-2026-39821 · CVE-2026-39852 · CVE-2026-39892 · CVE-2026-40682 · CVE-2026-41178 · CVE-2026-42502 · CVE-2026-42561 · CVE-2026-44431 · CVE-2026-44432 · CVE-2026-44660 · CVE-2026-44705 · CVE-2026-45820 · CVE-2026-47219 · CVE-2026-48526 · CVE-2026-48710 · CVE-2026-48746 · CVE-2026-49114 · CVE-2026-49825 · CVE-2026-49855 · CVE-2026-50559 · CVE-2026-54283 · CVE-2026-54399 · CVE-2026-54428 · CVE-2026-55831 · CVE-2026-55833 · CVE-2026-56121 · CVE-2026-56746 · CVE-2026-56819 · CVE-2026-56853 · CVE-2026-56858 · CVE-2026-56859 · CVE-2026-56860 · CVE-2026-56862 · CVE-2026-58059 · CVE-2026-59296 · CVE-2026-59879 · CVE-2026-59884 · CVE-2026-59885 · CVE-2026-59886 · CVE-2026-59899 · CVE-2026-62243 · CVE-2026-62384 · CVE-2026-63209 · CVE-2026-63374 · CVE-2026-65898 · CVE-2026-65918 · CVE-2026-66007 · CVE-2026-67213 · CVE-2026-67214 · CVE-2026-67312 · CVE-2026-68494 · CVE-2026-68497 · CVE-2026-68770 · CVE-2026-69097 · CVE-2026-69112 · CVE-2026-69152 · CVE-2026-69153 · CVE-2026-69243 · CVE-2026-69244 · CVE-2026-71281 · CVE-2026-73086 · CVE-2026-73088 · CVE-2026-73089 · CVE-2026-73415 · CVE-2026-73417 · CVE-2026-73502 · CVE-2026-73508 · CVE-2026-73620 · CVE-2026-73622 · CVE-2026-73623 · CVE-2026-73624 · CVE-2026-73625 · CVE-2026-73627 · CVE-2026-73646 · CVE-2026-75838 · CVE-2026-75899 · CVE-2026-75931 · CVE-2026-75975 · CVE-2026-76098 · CVE-2026-76169 · CVE-2026-76172 · CVE-2026-76222 · CVE-2026-76905 · CVE-2026-77354 · CVE-2026-77874 · CVE-2026-78676 · CVE-2026-78677 · CVE-2026-78679 · CVE-2026-78682 · CVE-2026-79674 · CVE-2026-79675 · CVE-2026-80205 · CVE-2026-81722 · CVE-2026-81724 · CVE-2026-81727 · CVE-2026-82397 · CVE-2026-82417 · CVE-2026-84292 · CVE-2026-84375 · CVE-2026-84394 · CVE-2026-84428 · CVE-2026-84445 · CVE-2026-84469 · CVE-2026-84504 · CVE-2026-84782 · CVE-2026-84961 · CVE-2026-85124 · CVE-2026-85152 · CVE-2026-85525 · CVE-2026-86049 · CVE-2026-86332 · CVE-2026-87776 · CVE-2026-87817 · CVE-2026-87819 · CVE-2026-88029 · CVE-2026-88031 · CVE-2026-89418 · CVE-2026-89425 · CVE-2026-91777 · CVE-2026-91990 · CVE-2026-92599 · CVE-2026-93599 · CVE-2026-93657 · CVE-2026-93749 · CVE-2026-96749 · CVE-2026-102831 · CVE-2026-102925 · CVE-2026-102930 · CVE-2026-102937 · CVE-2026-102938 · CVE-2026-103262 · CVE-2026-104851 · CVE-2026-105744
RHSA-2026:86891: Red Hat Security Advisory: RHOAI 3.5.2 - Red Hat OpenShift AI
CVE-2024-14029 · CVE-2026-13697 · CVE-2026-15679 · CVE-2026-15789 · CVE-2026-18427 · CVE-2026-19534 · CVE-2026-37237 · CVE-2026-49825 · CVE-2026-49855 · CVE-2026-54284 · CVE-2026-56859 · CVE-2026-59296 · CVE-2026-59893 · CVE-2026-62243 · CVE-2026-62384 · CVE-2026-63209 · CVE-2026-63374 · CVE-2026-66007 · CVE-2026-68494 · CVE-2026-68497 · CVE-2026-69097 · CVE-2026-69112 · CVE-2026-69152 · CVE-2026-69243 · CVE-2026-69244 · CVE-2026-71281 · CVE-2026-71491 · CVE-2026-73417 · CVE-2026-73502 · CVE-2026-73508 · CVE-2026-73646 · CVE-2026-75838 · CVE-2026-75899 · CVE-2026-75931 · CVE-2026-75975 · CVE-2026-76098 · CVE-2026-76169 · CVE-2026-76172 · CVE-2026-76222 · CVE-2026-76905 · CVE-2026-77354 · CVE-2026-77874 · CVE-2026-78676 · CVE-2026-78677 · CVE-2026-78679 · CVE-2026-78682 · CVE-2026-79674 · CVE-2026-79675 · CVE-2026-80205 · CVE-2026-81722 · CVE-2026-81724 · CVE-2026-81725 · CVE-2026-81726 · CVE-2026-81727 · CVE-2026-82397 · CVE-2026-82417 · CVE-2026-84292 · CVE-2026-84375 · CVE-2026-84381 · CVE-2026-84382 · CVE-2026-84394 · CVE-2026-84428 · CVE-2026-84445 · CVE-2026-84469 · CVE-2026-84504 · CVE-2026-84782 · CVE-2026-84961 · CVE-2026-85124 · CVE-2026-85152 · CVE-2026-85525 · CVE-2026-86332 · CVE-2026-87776 · CVE-2026-87817 · CVE-2026-87819 · CVE-2026-88029 · CVE-2026-88031 · CVE-2026-89425 · CVE-2026-91990 · CVE-2026-93348 · CVE-2026-93599 · CVE-2026-93657 · CVE-2026-93749 · CVE-2026-96749 · CVE-2026-96775 · CVE-2026-102925 · CVE-2026-102930 · CVE-2026-102937 · CVE-2026-102938 · CVE-2026-102990 · CVE-2026-104851 · CVE-2026-104852 · CVE-2026-104861 · CVE-2026-104873
- Source published
- Sep 4, 2026, 10:24:27 AM (timezone not stated)
- Source modified
- Sep 4, 2026, 4:06:04 PM (timezone not stated)
- Saved here
- 11 Nov 2026 17:01:23 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
nvd · CVE-2026-84428
Publishedfastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later.
Additional publisher context
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Analyzed
Weakness classifications: CWE-178
Original publisher date fields
published: 2026-09-04T11:17:19.317
lastModified: 2026-09-15T19:54:32.420
1 source CPE criteria · context only
- cpe:2.3:a:fastify:fastify:*:*:*:*:*:node.js:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
- Source published
- 4 Sep 2026 11:17:19 UTC
- Source modified
- 15 Sep 2026 19:54:32 UTC
- Saved here
- 25 Oct 2026 16:19:16 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
osv · GHSA-9q9j-q6p8-xq58
Published### Impact Fastify lowercases header-schema property names before compiling the schema, because Node.js stores request header names in lowercase. That normalization was incomplete: it lowercased only top-level `properties` keys and the root `required` array, and did not lowercase the JSON Schema Draft 7 `dependencies` keyword (its trigger keys and dependent property names) or names in nested subschemas. As a result, a header schema that uses `dependencies` to require one header when another is present (for example `X-Admin` requiring `X-Admin-Token`) never matches the lowercased request headers, so the dependency assertion is silently skipped. An unauthenticated remote client can send the header that activates a privileged path while omitting the header the dependency was meant to require, bypassing a schema-enforced security control. The header schema is idiomatic, valid JSON Schema Draft 7, and no custom validator, malformed request, or misconfiguration is required. ### Patches Header-schema names are now normalized across all schema positions (`properties`, `required`, `dependencies`, `dependentRequired`, `dependentSchemas`, and nested subschemas). Patched in fastify `5.12.2`. The fix is also included in the `6.0.0` release. Header schemas referenced through an external shared `$ref` (registered with `addSchema`) are not reached by this normalization and now emit an `FSTSEC002` startup warning; inline the header schema to keep case-insensitive assertions in effect. ### Workarounds If upgrading is not immediately possible, write header-schema names in lowercase so the `dependencies` and other case-sensitive assertions match Node's lowercased request headers, or enforce the cross-header requirement in an `onRequest` or `preValidation` hook instead of the schema.
- Source published
- 30 Sep 2026 23:44:27 UTC
- Source modified
- 1 Oct 2026 00:00:05 UTC
- Saved here
- 24 Oct 2026 13:17:17 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Publisher rating · HIGH