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Vulnerability details: VCID-mjfs-h1jx-2yar
Vulnerability ID VCID-mjfs-h1jx-2yar
Aliases CVE-2026-3419
GHSA-573f-x89g-hqp9
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (4)
CWE-185 Incorrect Regular Expression
CWE-625 Permissive Regular Expression
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 5.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-3419.json
epss 0.00017 https://api.first.org/data/v1/epss?cve=CVE-2026-3419
epss 0.00017 https://api.first.org/data/v1/epss?cve=CVE-2026-3419
cvssv3.1 5.3 https://cna.openjsf.org/security-advisories.html
generic_textual MODERATE https://cna.openjsf.org/security-advisories.html
ssvc Track https://cna.openjsf.org/security-advisories.html
cvssv3.1 5.3 https://github.com/advisories/GHSA-573f-x89g-hqp9
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-573f-x89g-hqp9
generic_textual MODERATE https://github.com/advisories/GHSA-573f-x89g-hqp9
ssvc Track https://github.com/advisories/GHSA-573f-x89g-hqp9
cvssv3.1 5.3 https://github.com/fastify/fastify
generic_textual MODERATE https://github.com/fastify/fastify
cvssv3.1 5.3 https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
generic_textual MODERATE https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
ssvc Track https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
cvssv3.1 5.3 https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
cvssv3.1_qr MODERATE https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
generic_textual MODERATE https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
ssvc Track https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
cvssv3.1 5.3 https://httpwg.org/specs/rfc9110.html#field.content-type
generic_textual MODERATE https://httpwg.org/specs/rfc9110.html#field.content-type
ssvc Track https://httpwg.org/specs/rfc9110.html#field.content-type
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2026-3419
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2026-3419
cvssv3.1 5.3 https://www.cve.org/CVERecord?id=CVE-2026-3419
generic_textual MODERATE https://www.cve.org/CVERecord?id=CVE-2026-3419
ssvc Track https://www.cve.org/CVERecord?id=CVE-2026-3419
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-3419.json
https://api.first.org/data/v1/epss?cve=CVE-2026-3419
https://github.com/fastify/fastify
2445295 https://bugzilla.redhat.com/show_bug.cgi?id=2445295
67f6c9b32cb3623d3c9470cc17ed830dd2f083d7 https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
CVE-2026-3419 https://nvd.nist.gov/vuln/detail/CVE-2026-3419
CVERecord?id=CVE-2026-3419 https://www.cve.org/CVERecord?id=CVE-2026-3419
GHSA-573f-x89g-hqp9 https://github.com/advisories/GHSA-573f-x89g-hqp9
GHSA-573f-x89g-hqp9 https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
rfc9110.html#field.content-type https://httpwg.org/specs/rfc9110.html#field.content-type
security-advisories.html https://cna.openjsf.org/security-advisories.html
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-3419.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://cna.openjsf.org/security-advisories.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-09T14:55:13Z/ Found at https://cna.openjsf.org/security-advisories.html
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/advisories/GHSA-573f-x89g-hqp9
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-09T14:55:13Z/ Found at https://github.com/advisories/GHSA-573f-x89g-hqp9
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/fastify/fastify
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-09T14:55:13Z/ Found at https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

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required

unchanged

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-09T14:55:13Z/ Found at https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://httpwg.org/specs/rfc9110.html#field.content-type
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

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unchanged

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-09T14:55:13Z/ Found at https://httpwg.org/specs/rfc9110.html#field.content-type
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-3419
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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required

unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://www.cve.org/CVERecord?id=CVE-2026-3419
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

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none

required

unchanged

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-09T14:55:13Z/ Found at https://www.cve.org/CVERecord?id=CVE-2026-3419
Exploit Prediction Scoring System (EPSS)
Percentile 0.04195
EPSS Score 0.00017
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T16:54:46.449635+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/3xxx/CVE-2026-3419.json 38.6.0