When regex-based content-type parsers are in use (a documented Fastify feature), the malformed value is matched against registered parsers using the full string including the trailing garbage. This means a request with an invalid content-type may be routed to and processed by a parser it should never have reached.
Impact:
An attacker can send requests with RFC-invalid Content-Type headers that bypass validity checks, reach content-type parser matching, and be processed by the server. Requests that should be rejected at the validation stage are instead handled as if the content-type were valid.
Workarounds:
Deploy a WAF rule to protect against this
Fix:
The fix is available starting with v5.8.1.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-573f-x89g-hqp9 | Fastify's Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation |
Wed, 18 Mar 2026 19:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:a:fastify:fastify:*:*:*:*:*:node.js:*:* |
Mon, 09 Mar 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Mon, 09 Mar 2026 10:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Fastify
Fastify fastify |
|
| Vendors & Products |
Fastify
Fastify fastify |
Sat, 07 Mar 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-625 | |
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Fri, 06 Mar 2026 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Fastify incorrectly accepts malformed `Content-Type` headers containing trailing characters after the subtype token, in violation of RFC 9110 §8.3.1(https://httpwg.org/specs/rfc9110.html#field.content-type). For example, a request sent with Content-Type: application/json garbage passes validation and is processed normally, rather than being rejected with 415 Unsupported Media Type. When regex-based content-type parsers are in use (a documented Fastify feature), the malformed value is matched against registered parsers using the full string including the trailing garbage. This means a request with an invalid content-type may be routed to and processed by a parser it should never have reached. Impact: An attacker can send requests with RFC-invalid Content-Type headers that bypass validity checks, reach content-type parser matching, and be processed by the server. Requests that should be rejected at the validation stage are instead handled as if the content-type were valid. Workarounds: Deploy a WAF rule to protect against this Fix: The fix is available starting with v5.8.1. | |
| Title | Fastify's Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation | |
| Weaknesses | CWE-185 | |
| References |
|
|
| Metrics |
cvssV3_1
|
Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-03-09T14:55:21.011Z
Reserved: 2026-03-01T18:56:49.613Z
Link: CVE-2026-3419
Updated: 2026-03-09T14:55:17.583Z
Status : Analyzed
Published: 2026-03-06T18:16:22.213
Modified: 2026-03-18T19:11:46.967
Link: CVE-2026-3419
OpenCVE Enrichment
Updated: 2026-04-16T11:30:15Z
Github GHSA