CVE-2021-3647Public exploitNetwork attack vector

Hostname spoofing via mixed slash-backslash scheme delimiters

Published Jul 16, 2021 · Updated Aug 3, 2024

Hostname spoofing in medialize URI.js before 1.19.7 allows remote attackers to bypass URL-based security decisions with crafted URLs. The parser in src/URI.js treats mixed slash and backslash scheme delimiters as a path-like form, causing affected releases to return an empty hostname instead of the embedded host. Exposure requires a consuming application to make a security decision from that hostname; consequences include allowlist bypass, open redirect, or SSRF.

CVSS severity5.3
Medium
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hostname spoofing in medialize URI.js before 1.19.7 allows remote attackers to bypass URL-based security decisions with crafted URLs. The parser in src/URI.js treats mixed slash and backslash scheme delimiters as a path-like form, causing affected releases to return an empty hostname instead of the embedded host. Exposure requires a consuming application to make a security decision from that hostname; consequences include allowlist bypass, open redirect, or SSRF.

The record

CVE
CVE-2021-3647
Published
Jul 16, 2021
Updated
Aug 3, 2024
Vendor
medialize
Product
URI.js
Classifications
CWE-601
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=unspecified <=1.19.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

medialize · URI.jsversion=unspecified <=1.19.6

Published CVSS scores

5.3huntr.dev CNACVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')

Public exploit references

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Technologies

Your stack

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Your stack

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