CVE-2023-41330 (published 2023-09-06T18:15Z)

knplabs/knp-snappy is a PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page.\n## Issue\n\nOn March 17th the vulnerability CVE-2023-28115 was disclosed, allowing an attacker to gain remote code execution through PHAR deserialization. Version 1.4.2 added a check `if (\\strpos($filename, 'phar://') === 0)` in the `prepareOutput` function to resolve this CVE, however if the user is able to control the second parameter of the `generateFromHtml()` function of Snappy, it will then be passed as the `$filename` parameter in the `prepareOutput()` function. In the original vulnerability, a file name with a `phar://` wrapper could be sent to the `fileExists()` function, equivalent to the `file_exists()` PHP function. This allowed users to trigger a deserialization on arbitrary PHAR files. To fix this issue, the string is now passed to the `strpos()` function and if it starts with `phar://`, an exception is raised. However, PHP wrappers being case insensitive, this patch can be bypassed using `PHAR://` instead of `phar://`. A successful exploitation of this vulnerability allows executing arbitrary code and accessing the underlying filesystem. The attacker must be able to upload a file and the server must be running a PHP version prior to 8. This issue has been addressed in commit `d3b742d61a` which has been included in version 1.4.3. Users are advised to upgrade. Users unable to upgrade should ensure that only trusted users may submit data to the `AbstractGenerator->generate(...)` function.\n

CVSS v3 base score: 9.8, CRITICAL (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-502
cwe_name: Deserialization of Untrusted Data
description: 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.
         
         

Fix information:
repo_url: https://github.com/KnpLabs/snappy
commit_details: repo_url: https://github.com/KnpLabs/snappy
author: Alessandro Pozzi
author_date: 2023-09-06 17:24:48+02:00
msg: Merge pull request #488 from KnpLabs/fix/security-advisory-GHSA-92rv-4j2h-8mjj

fix: security advisory GHSA-92rv-4j2h-8mjj
repository: repo_url: https://github.com/KnpLabs/snappy
repo_name: KnpLabs/snappy
description: PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page. Wrapper for wkhtmltopdf/wkhtmltoimage
repo_language: PHP
owner: KnpLabs