CVE-2026-15144Network attack vector

Rate-limit bypass via noncanonical IPv6 bucket keys

Published Jul 29, 2026 · Updated Jul 29, 2026

Rate-limit bypass in @fastify/rate-limit before 11.2.0 allows remote attackers to evade request throttling through crafted IPv6 identities. The default key generator uses the verbatim request.ip string, so address rotation and alternate spellings create independent buckets. Exploitation requires IPv6 to reach the origin through a trusted proxy and permits additional requests to protected endpoints.

CVSS severity7.3
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Rate-limit bypass in @fastify/rate-limit before 11.2.0 allows remote attackers to evade request throttling through crafted IPv6 identities. The default key generator uses the verbatim request.ip string, so address rotation and alternate spellings create independent buckets. Exploitation requires IPv6 to reach the origin through a trusted proxy and permits additional requests to protected endpoints.

The record

CVE
CVE-2026-15144
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
Fastify
Product
@fastify/rate-limit
Classifications
CWE-307, CWE-770, T1110
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <11.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fastify · @fastify/rate-limitversion=0 <11.2.0

Published CVSS scores

7.3OpenJS FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-770Allocation of Resources Without Limits or Throttling
T1110Brute Force

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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