Microsoft · fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization
Affects MicrosoftSource GCVE Database
Not known to be exploited · CVSS 4.8 Medium · fixed in 4.2.3 : update Microsoft when convenient.
Data as of 14 Nov 2026, 08:48 UTC
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 13 Nov 2026.
What to do
Upgrade fast-uri to 4.2.3, 3.1.9 or 2.4.8.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| fast-urifast-uri | Affected
| Fixed in
|
| fast-urifast-uri | Affected
| Fixed in
|
| fast-urifast-uri | Affected
| Fixed in
|
npmfast-uripkg:npm/fast-uriOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle