CVE-2021-3647
Open Redirect in medialize/URI.js
URI.js is vulnerable to URL Redirection to Untrusted Site
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Open Redirect in medialize/URI.js
URI.js is vulnerable to URL Redirection to Untrusted Site
- Record
CVE-2021-3647- CVSS 3.0
- 5.3 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
EUVDEUVD-2021-1450
URI.js is vulnerable to URL Redirection to Untrusted Site
- Record
EUVD-2021-1450- CVSS 3.0
- 5.3 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-89gv-h8wf-cg8r
URIjs Vulnerable to Hostname spoofing via backslashes in URL
Impact
If using affected versions to determine a URL's hostname, the hostname can be spoofed by using a combination of backslash (\) and slash (/) characters as part of the scheme delimiter, e.g. scheme:/\/\/\hostname. If the hostname is used in security decisions, the decision may be incorrect.
Depending on library usage and attacker intent, impacts may include allow/block list bypasses, SSRF attacks, open redirects, or other undesired behavior.
Example URL: https:/\/\/\expected-example.com/path
Escaped string: https:/\\/\\/\\expected-example.com/path (JavaScript strings must escape backslash)
Affected versions incorrectly return no hostname. Patched versions correctly return expected-example.com. Patched versions match the behavior of other parsers which implement the WHATWG URL specification, including web browsers and Node's built-in URL class.
Patches
Version 1.19.7 is patched against all known payload variants.
References
https://github.com/medialize/URI.js/releases/tag/v1.19.7 (fix for this particular bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.6 (fix for related bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.4 (fix for related bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.3 (fix for related bypass) PR #233 (initial fix for backslash handling)
For more information
If you have any questions or comments about this advisory, open an issue in https://github.com/medialize/URI.js
Reporter credit
- Record
GHSA-89gv-h8wf-cg8r- CVSS 3.0
- 5.3 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
NVD
URI.js is vulnerable to URL Redirection to Untrusted Site
- Record
CVE-2021-3647- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 3.0
- 5.3 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS 2.0
- 5.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
OSV
URI.js is vulnerable to URL Redirection to Untrusted Site
- Record
CVE-2021-3647- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-89gv-h8wf-cg8r
URIjs Vulnerable to Hostname spoofing via backslashes in URL
Impact
If using affected versions to determine a URL's hostname, the hostname can be spoofed by using a combination of backslash (\) and slash (/) characters as part of the scheme delimiter, e.g. scheme:/\/\/\hostname. If the hostname is used in security decisions, the decision may be incorrect.
Depending on library usage and attacker intent, impacts may include allow/block list bypasses, SSRF attacks, open redirects, or other undesired behavior.
Example URL: https:/\/\/\expected-example.com/path
Escaped string: https:/\\/\\/\\expected-example.com/path (JavaScript strings must escape backslash)
Affected versions incorrectly return no hostname. Patched versions correctly return expected-example.com. Patched versions match the behavior of other parsers which implement the WHATWG URL specification, including web browsers and Node's built-in URL class.
Patches
Version 1.19.7 is patched against all known payload variants.
References
https://github.com/medialize/URI.js/releases/tag/v1.19.7 (fix for this particular bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.6 (fix for related bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.4 (fix for related bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.3 (fix for related bypass) PR #233 (initial fix for backslash handling)
For more information
If you have any questions or comments about this advisory, open an issue in https://github.com/medialize/URI.js
Reporter credit
- Record
GHSA-89gv-h8wf-cg8r- CVSS 3.0
- 5.3 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-3647
URI.js is vulnerable to URL Redirection to Untrusted Site
- Record
UBUNTU-CVE-2021-3647- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 3.0
- 5.3 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
urijsnpm |
before 1.19.7 | 1.19.7 |
node-uri-jsUbuntu:20.04:LTS |
All versions, plus listed versions 4.2.2+dfsg-44.2.2+dfsg-5 |
None known |
node-uri-jsUbuntu:22.04:LTS |
All versions, plus listed versions 4.4.0+dfsg-54.4.0+dfsg-7 |
None known |
node-uri-jsUbuntu:24.04:LTS |
All versions, plus listed versions 4.4.0+dfsg-8 |
None known |
node-uri-jsUbuntu:25.10 |
All versions, plus listed versions 4.4.0+dfsg-8 |
None known |
node-uri-jsUbuntu:26.10 |
All versions, plus listed versions 4.4.0+dfsg-94.4.0+dfsg-10 |
None known |
node-uri-jsUbuntu:26.04:LTS |
All versions, plus listed versions 4.4.0+dfsg-84.4.0+dfsg-9 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-3647 is a medium vulnerability (CVSS 5.3) in Medialize Medialize/uri.js, published July 16, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.91%, the 60th percentile. Fixed in urijs 1.19.7.
References
huntr.dev/bounties/1625558772840-medialize/URI.js
github.com/medialize/URI.js/commit/ac43ca8f80c042f0256fb551ea5203863dec4481