CVE Intelligence
Medium Input validation

CVE-2026-110180 — fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization

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.

Published Oct 20, 2026 · Updated Oct 20, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: openjs

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+2
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.21%
ahead of 10% of scored CVEs · Oct 20, 2026
Affects
Fast-uri
Fast-uri
CVSS base
4.8
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Fast-uri Fast-uri).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes matching the vulnerability class (input validation), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Fast-uri Fast-uri ≥ 2.4.2 and < 2.4.8≥ 3.1.3 and < 3.1.9≥ 4.0.1 and < 4.2.3 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
4.8 CVSS 3.1 Medium 2.2 2.5 ce714d77-add3-4f53-aff5-83d477b104bb via NIST National Vulnerability Database
4.8 CVSS 3.1 Medium — — openjs via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N (score shown at the top: ce714d77-add3-4f53-aff5-83d477b104bb)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-20 · Improper Input Validation

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Source status changed · Received → Awaiting Analysis
    Oct 20, 2026 · NIST National Vulnerability Database
  • SSVC assessment updated
    Oct 20, 2026 · CVE Program (cve.org) e CISA ADP
  • Affected products added · fast-uri/fast-uri
    Oct 20, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 20, 2026
  • CVSS changed · 4.8
    Oct 20, 2026 · NIST National Vulnerability Database
  • Source status changed · → Received
    Oct 20, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 20, 2026 · Alertas do Telegram
  • CVE published
    Oct 20, 2026 · openjs

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 20, 2026 – Oct 20, 2026
  • 1× Official description updated · Oct 20, 2026 – Oct 20, 2026

References

2 on the record

Elsewhere on this site

Fast-uri
every CVE for this vendor
Input validation
same class
CWE-20
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-110725 fast-uri vulnerable to scheme injection via an unescaped first-segment colon in suffix references 1d
  • CVE-2026-110306 fast-uri vulnerable to URI scheme spoofing via percent-encoded scheme decoding 1d
  • CVE-2026-110095 fast-uri vulnerable to improper path equivalence in relative reference normalization 1d
  • CVE-2026-86818 fast-uri vulnerable to mailto header injection via percent-encoded field-name desynchronization Sep 15, 2026
  • CVE-2026-86472 fast-uri vulnerable to inconsistent host case normalization via percent-encoded octets Sep 15, 2026
  • CVE-2026-84394 fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority Sep 3, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-110180 is "fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization", rated Medium. It affects Fast-uri (Fast-uri); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.8 describes technical severity. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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