CVE Vulnerabilities


Deserialization of Untrusted Data

Published: Feb 21, 2024 | Modified: Feb 21, 2024
CVSS 3.x
CVSS 2.x

php-svg-lib is a scalable vector graphics (SVG) file parsing/rendering library. Prior to version 0.5.2, php-svg-lib fails to validate that font-family doesnt contain a PHAR url, which might leads to RCE on PHP < 8.0, and doesnt validate if external references are allowed. This might leads to bypass of restrictions or RCE on projects that are using it, if they do not strictly revalidate the fontName that is passed by php-svg-lib. The Style::fromAttributes(), or the Style::parseCssStyle() should check the content of the font-family and prevents it to use a PHAR url, to avoid passing an invalid and dangerous fontName value to other libraries. The same check as done in the Style::fromStyleSheets might be reused. Libraries using this library as a dependency might be vulnerable to some bypass of restrictions, or even remote code execution, if they do not double check the value of the fontName that is passed by php-svg-lib. Version 0.5.2 contains a fix for this issue.


The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

Extended Description

It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security – which is a dangerous security assumption. Data that is untrusted can not be trusted to be well-formed. When developers place no restrictions on “gadget chains,” or series of instances and method invocations that can self-execute during the deserialization process (i.e., before the object is returned to the caller), it is sometimes possible for attackers to leverage them to perform unauthorized actions, like generating a shell.

Potential Mitigations

  • Make fields transient to protect them from deserialization.
  • An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.