Skip to main content
VulnerabilityPublished

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

Affects @fastify/accepts-serializerSource GCVE Database

0
Authoritative record:CVE-2026-7768· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 6.0.4 soon.

Data as of 27 Oct 2026, 00:07 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 6.0.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade @fastify/accepts-serializer to 6.0.4.

Affected software

ProductAffectedFixed in
npm@fastify/accepts-serializerAffected
  • <6.0.4
Fixed in
  • 6.0.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

### Impact `@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. Under sustained load, this can exhaust the Node.js heap and crash the process. ### Patches Update to `@fastify/accepts-serializer >= 6.0.4`. The cache is now bounded by an LRU with a default size of 100 entries, configurable via the new `cacheSize` plugin option. ### Workarounds None. Upgrade is required.

References

Community reviews

Loading reviews…