CVE-2025-32442Network attack vector

Validation bypass via incorrect Content-Type normalization

Published Apr 18, 2025 · Updated Aug 22, 2025

Improper input validation in Fastify 4.29.0 and 5.0.0 through 5.3.1 allows remote attackers to bypass request-body validation. The getEssenceMediaType function splits Content-Type only at a semicolon, so whitespace-bearing variants produce a schema lookup key that does not match the configured media type. Exposure requires a route using schema.body.content; an invalid body can then reach its handler without the intended integrity checks.

CVSS severity7.5
High
EPSS probability0.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Fastify 4.29.0 and 5.0.0 through 5.3.1 allows remote attackers to bypass request-body validation. The getEssenceMediaType function splits Content-Type only at a semicolon, so whitespace-bearing variants produce a schema lookup key that does not match the configured media type. Exposure requires a route using schema.body.content; an invalid body can then reach its handler without the intended integrity checks.

The record

CVE
CVE-2025-32442
Published
Apr 18, 2025
Updated
Aug 22, 2025
Vendor
Fastify
Product
Fastify
Classifications
CWE-1287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 4.29.0
  2. Affected versionversion=>= 5.0.0, < 5.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fastify · Fastifyversion== 4.29.0; version=>= 5.0.0, < 5.3.2

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1287Improper Validation of Specified Type of Input
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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