What’s Vulnerable › Vulnerabilities

CVE-2026-7768: @fastify/accepts-serializer vulnerable to Denial of Service via Unbounded Accept Header Cache Growth

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-04 · updated 2026-06-17
• Weakness: CWE-770

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.

Affected products

• @fastify/accepts-serializer: before 6.0.4 — fixed in 6.0.4

How to fix

Upgrade to a fixed version: @fastify/accepts-serializer 6.0.4. Check the vendor advisory for mitigations.

References

• https://cna.openjsf.org/security-advisories.html
• https://github.com/fastify/fastify-accepts-serializer/security/advisories/GHSA-qxhc-wx3p-2wmg

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