CVE-2021-21706

ZipArchive::extractTo may extract outside of destination dir

Severity Score

6.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

En PHP versiones de 7.3.x por debajo de 7.3.31, versiones 7.4.x por debajo de 7.4.24 y 8.0.x por debajo de 8.0.11, en el entorno de Microsoft Windows, la función ZipArchive::extractTo puede ser engañada para escribir un archivo fuera del directorio de destino cuando es extraído un archivo ZIP, causando así potencialmente una creación o sobreescritura de archivos, sujeto a los permisos del Sistema Operativo

An update that fixes 18 vulnerabilities, contains one feature is now available. This update for php7 fixes the following issues. Fixed out-of-bounds read due to insufficient input validation in imageloadfont. Fixed buffer overflow in hash_update on long parameter. Fixed an uncontrolled recursion in the phar uncompressor while decompressing "quines" gzip files. Fixed a bug which could lead an attacker to set an insecure cookie that will treated as secure in the victim's browser.

*Credits: reported by vi at hackberry dot xyz

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

Medium

Authentication

None

Confidentiality

None

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-01-04 CVE Reserved
2021-10-04 CVE Published
2024-09-16 CVE Updated
2025-07-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-24: Path Traversal: '../filedir'

CAPEC

References (2)

URL	Tag	Source
https://security.netapp.com/advisory/ntap-20211029-0007	Third Party Advisory

URL	Date	SRC

URL	Date	SRC
https://bugs.php.net/bug.php?id=81420	2021-11-03

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Php Search vendor "Php"	Php Search vendor "Php" for product "Php"	>= 7.3.0 < 7.3.31 Search vendor "Php" for product "Php" and version " >= 7.3.0 < 7.3.31"	-	Affected	in	Microsoft Search vendor "Microsoft"	Windows Search vendor "Microsoft" for product "Windows"	-	-	Safe
Php Search vendor "Php"	Php Search vendor "Php" for product "Php"	>= 7.4.0 < 7.4.24 Search vendor "Php" for product "Php" and version " >= 7.4.0 < 7.4.24"	-	Affected	in	Microsoft Search vendor "Microsoft"	Windows Search vendor "Microsoft" for product "Windows"	-	-	Safe
Php Search vendor "Php"	Php Search vendor "Php" for product "Php"	>= 8.0.0 < 8.0.11 Search vendor "Php" for product "Php" and version " >= 8.0.0 < 8.0.11"	-	Affected	in	Microsoft Search vendor "Microsoft"	Windows Search vendor "Microsoft" for product "Windows"	-	-	Safe