@fastify/accepts-serializer cached serializer-selection results keyed by the request Accept header without a size limit or eviction policy. A remote unauthenticated client could send many distinct but matching Accept header variants to make the cache grow unbounded, eventually exhausting the Node.js heap and crashing the process. Versions <= 6.0.3 are affected. Update to 6.0.4 or later, which bounds the cache via an LRU with a default size of 100 entries, configurable through the new cacheSize plugin option.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-qxhc-wx3p-2wmg @fastify/accepts-serializer Vulnerable to Denial of Service via Unbounded Accept Header Cache Growth
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 06 May 2026 09:45:00 +0000

Type Values Removed Values Added
First Time appeared Fastify
Fastify fastify-accepts-serializer
Vendors & Products Fastify
Fastify fastify-accepts-serializer

Mon, 04 May 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 04 May 2026 19:30:00 +0000

Type Values Removed Values Added
Description @fastify/accepts-serializer cached serializer-selection results keyed by the request Accept header without a size limit or eviction policy. A remote unauthenticated client could send many distinct but matching Accept header variants to make the cache grow unbounded, eventually exhausting the Node.js heap and crashing the process. Versions <= 6.0.3 are affected. Update to 6.0.4 or later, which bounds the cache via an LRU with a default size of 100 entries, configurable through the new cacheSize plugin option.
Title @fastify/accepts-serializer vulnerable to Denial of Service via Unbounded Accept Header Cache Growth
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-05-04T19:50:16.465Z

Reserved: 2026-05-04T11:50:02.918Z

Link: CVE-2026-7768

cve-icon Vulnrichment

Updated: 2026-05-04T19:50:12.504Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-04T20:16:21.107

Modified: 2026-05-07T15:11:09.037

Link: CVE-2026-7768

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-06T09:22:37Z

Weaknesses