CVE-2021-21705

Name: CVE-2021-21705
Creator: NVD / NIST
Published: 2021-10-04T04:15:08.21+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 1.94%

Last modified Jun 17, 2026

CVE-2021-21705 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using URL validation functionality via filter_var() function with FILTER_VALIDATE_URL parameter, an URL with invalid password field can be accepted as valid. This can lead to the code incorrectly parsing the URL and potentially leading to other security implications - like contacting a wrong server or making a wrong access decision.. EPSS estimates a 1.94% chance of exploitation in the next 30 days.

Description

In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using URL validation functionality via filter_var() function with FILTER_VALIDATE_URL parameter, an URL with invalid password field can be accepted as valid. This can lead to the code incorrectly parsing the URL and potentially leading to other security implications - like contacting a wrong server or making a wrong access decision.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

1.94%

77.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Php	Php	>= 7.3.0, < 7.3.29
Php	Php	>= 7.4.0, < 7.4.21
Php	Php	>= 8.0.0, < 8.0.8
Netapp	Clustered Data Ontap	All versions
Oracle	Sd-Wan Aware	8.2

References

https://bugs.php.net/bug.php?id=81122Exploit, Issue Tracking, Patch, Vendor Advisory
https://security.gentoo.org/glsa/202209-20Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0006/Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Vendor Advisory
https://bugs.php.net/bug.php?id=81122Exploit, Issue Tracking, Patch, Vendor Advisory
https://security.gentoo.org/glsa/202209-20Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0006/Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Vendor Advisory

Timeline

Published: Oct 4, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21705?

How severe is CVE-2021-21705?

CVE-2021-21705 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 1.94% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21705?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21705?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST