Fastify's Content-Type header tab character allows body validation bypass

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0086, the 58th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the GitHub Advisory Database, published 2 Feb 2026. New records show when each source confirmed them.

Sources

• GitHub Advisory Database: GHSA-jx2c-rxcm-jvmq
• OSV: GHSA-jx2c-rxcm-jvmq
• github.com/fastify/fastify/security/advisories/GHSA-jx2c-rxcm-jvmq
• nvd.nist.gov/vuln/detail/CVE-2026-25223
• github.com/fastify/fastify/commit/32d7b6add39ddf082d92579a58bea7018c5ac821
• hackerone.com/reports/3464114
• fastify.dev/docs/latest/Reference/Validation-and-Serialization
• github.com/fastify/fastify
• github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/content-type-parser.js#L125
• github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/validation.js#L272

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.