CVE-2026-3419

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Source
https://cve.org/CVERecord?id=CVE-2026-3419
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-3419.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-3419
Aliases
Published
2026-03-06T17:50:58.714Z
Modified
2026-07-08T08:14:43.873283372Z
Severity
  • 5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
Summary
Fastify's Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation
Details

Fastify incorrectly accepts malformed Content-Type headers containing trailing characters after the subtype token, in violation of RFC 9110 ยง8.3.1(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.

Database specific 
{
    "cna_assigner": "openjs",
    "cwe_ids": [
        "CWE-185"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3419.json"
}
References

Affected packages

Git / github.com/fastify/fastify

Affected ranges

Type
GIT
Repo
https://github.com/fastify/fastify
Events
Introduced
e1e4fe75910c36e1b9ebb87026ca16c053a9c1f2
Fixed
073ff8132f350aaa53935231019499e983cb9794
Fixed
67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
Database specific 
{
    "extracted_events": [
        {
            "introduced": "5.7.2"
        },
        {
            "fixed": "5.8.1"
        }
    ],
    "cpe": "cpe:2.3:a:fastify:fastify:*:*:*:*:*:node.js:*:*",
    "source": [
        "CPE_RANGE",
        "REFERENCES"
    ]
}

Affected versions

v5.*
v5.7.2
v5.7.3
v5.7.4
v5.8.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-3419.json"