CVE-2021-21706

Name: CVE-2021-21706
Creator: NVD / NIST
Published: 2021-10-04T04:15:08.35+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.34%

Last modified Jun 17, 2026

CVE-2021-21706 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. In PHP versions 7.3.x below 7.3.31, 7.4.x below 7.4.24 and 8.0.x below 8.0.11, in Microsoft Windows environment, ZipArchive::extractTo may be tricked into writing a file outside target directory when extracting a ZIP file, thus potentially causing files to be created or overwritten, subject to OS permissions.. EPSS estimates a 1.34% chance of exploitation in the next 30 days.

Description

In PHP versions 7.3.x below 7.3.31, 7.4.x below 7.4.24 and 8.0.x below 8.0.11, in Microsoft Windows environment, ZipArchive::extractTo may be tricked into writing a file outside target directory when extracting a ZIP file, thus potentially causing files to be created or overwritten, subject to OS permissions.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.34%

67.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Php	Php	>= 7.3.0, < 7.3.31
Php	Php	>= 7.4.0, < 7.4.24
Php	Php	>= 8.0.0, < 8.0.11

References

https://bugs.php.net/bug.php?id=81420Issue Tracking, Patch, Vendor Advisory
https://security.netapp.com/advisory/ntap-20211029-0007/Third Party Advisory
https://bugs.php.net/bug.php?id=81420Issue Tracking, Patch, Vendor Advisory
https://security.netapp.com/advisory/ntap-20211029-0007/Third Party Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-21706?

How severe is CVE-2021-21706?

CVE-2021-21706 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.34% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21706?

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-2021-21706?

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

Scan your code now

Source: NVD / NIST