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VulnerabilityPublished Updated

CVE-2026-86472: Node ajv · fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv

Affects node-ajvSource GCVE Database

0

Not known to be exploited · CVSS 4.8 Medium · fixed in 2.4.7 : update node-ajv when convenient.

Data as of 28 Oct 2026, 22:28 UTC

CVSS 3.1 base score
4.8Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 2.4.7
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Sep 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

Affected software

ProductAffectedFixed in
Ubuntu 26.10node-ajvpkg:deb/ubuntu/node-ajv?arch=source&distro=stonkingOther threatsAffected
  • 8.17.1~ds+~3.0.1+~3.1.0-4build1 – 8.20.0~ds+~cs7.1.3-3
5 affected builds
Fixed in–
Ubuntu 26.04 LTSnode-ajvpkg:deb/ubuntu/node-ajv?arch=source&distro=resoluteOther threatsAffected
  • =8.12.0~ds+~2.1.1-5
  • =8.17.1~ds+~3.0.1+~3.1.0-2
  • =8.17.1~ds+~3.0.1+~3.1.0-4build1
Fixed in–
Ubuntu 24.04 LTSnode-ajvpkg:deb/ubuntu/node-ajv?arch=source&distro=nobleOther threatsAffected
  • =6.12.6-3
  • =8.12.0~ds+~2.1.1-4
Fixed in–
Ubuntu 22.04 LTSnode-ajvpkg:deb/ubuntu/node-ajv?arch=source&distro=jammyOther threatsAffected
  • =6.12.6-2
  • =6.12.6-3
Fixed in–
Ubuntu 20.04 LTSnode-ajvpkg:deb/ubuntu/node-ajv?arch=source&distro=focalOther threatsAffected
  • =6.10.2-1
Fixed in–
Ubuntu 18.04 LTSnode-ajvpkg:deb/ubuntu/node-ajv?arch=source&distro=bionicOther threatsAffected
  • =5.0.0-1
Fixed in–

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

Description

fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv. In versions before 2.4.7, from 3.0.0 through 3.1.7, and from 4.0.0 through 4.1.4, fast-uri folds the host to lowercase before it percent-decodes the host, so a percent-encoded uppercase octet such as %41 decodes to a literal A that is never folded. For a scheme-relative reference such as //host there is no scheme, so the host canonicalization that would normally repair this does not run, and parse, normalize, and equal then disagree on the same host. An application that makes a case-sensitive host decision on fast-uri output, for example a host allowlist or denylist that compares the parsed host or uses equal, can be steered past the check with a percent-encoded uppercase octet, and because hostnames are case-insensitive in DNS and HTTP the evading spelling still reaches the host the check meant to gate. The issue is fixed in fast-uri 2.4.7, 3.1.8, and 4.1.5, and users should upgrade to one of those versions or later. As a workaround, compare hosts case-insensitively by lowercasing the parsed host before any allowlist or denylist decision.

References

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