php php CVE-2021-21707 vulnerability in PHP and Other Products
Published on November 29, 2021

Special characters break path parsing in XML functions

product logo product logo product logo product logo product logo
In PHP versions 7.3.x below 7.3.33, 7.4.x below 7.4.26 and 8.0.x below 8.0.13, certain XML parsing functions, like simplexml_load_file(), URL-decode the filename passed to them. If that filename contains URL-encoded NUL character, this may cause the function to interpret this as the end of the filename, thus interpreting the filename differently from what the user intended, which may lead it to reading a different file than intended.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2021-21707 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

Improper Handling of Invalid Use of Special Elements

The product does not properly filter, remove, quote, or otherwise manage the invalid use of special elements in user-controlled input, which could cause adverse effect on its behavior and integrity.


Products Associated with CVE-2021-21707

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2021-21707 are published in these products:

PHP
 
NetApp Clustered Data Ontap
 
Canonical Ubuntu Linux
 
Debian Linux
 
Tenable Sc
 

Affected Versions

PHP Group PHP:

Exploit Probability

EPSS
0.56%
Percentile
67.95%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.