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VulnerabilityPublished

CVE-2026-110180: fast-uri · Improper Input Validation

Affects fast-uriSource CVE Database V5

0

Not known to be exploited · CVSS 4.8 Medium · fixed in 4.2.3 : update fast-uri when convenient.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score
4.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-20.

Patch
Available – fixed in 4.2.3, 3.1.9, 2.4.8
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 20 Oct 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 fast-uri to 4.2.3, 3.1.9 or 2.4.8.

Affected software

ProductAffectedFixed in
fast-urifast-uriAffected
  • >=4.0.1 <4.2.3
Fixed in
  • 4.2.3
fast-urifast-uriAffected
  • >=3.1.3 <3.1.9
Fixed in
  • 3.1.9
fast-urifast-uriAffected
  • >=2.4.2 <2.4.8
Fixed in
  • 2.4.8
npmfast-uripkg:npm/fast-uriOther threatsAffected
  • >=2.4.2 <2.4.8
  • >=3.1.3 <3.1.9
  • >=4.0.1 <4.2.3
Fixed in
  • 2.4.8
  • 3.1.9
  • 4.2.3

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 and serializer for Node.js. In versions from 2.4.2 through 2.4.7, from 3.1.3 through 3.1.8, and from 4.0.1 through 4.2.2, for HTTP-family schemes the canonicalizeHost() function passes the parsed host to the WHATWG URL parser and adopts its hostname without checking that the parser consumed the entire input as a host, so the authority can be silently rewritten: data before an at-sign is dropped and tab, carriage-return, and line-feed characters are stripped, with no error reported. An application that enforces host-based policy such as denylists, loopback filtering, redirect validation, or outbound proxy routing on one representation can then see the canonical host diverge from what it checked, allowing traffic to be steered to an unintended destination. The issue is fixed in fast-uri 2.4.8, 3.1.9, and 4.2.3, and users should upgrade to one of these versions or later. As a workaround, reject an authority that contains more than one at-sign or any tab, carriage-return, or line-feed before calling fast-uri, or treat any non-empty parse error as fatal and compare hosts only from the same parse result.

References

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