knplabs knp-snappy 1.4.2 prepareOutput filename deserialization

Summaryinfo

A vulnerability was found in knplabs knp-snappy 1.4.2. It has been declared as critical. Affected by this issue is the function prepareOutput. Such manipulation of the argument filename leads to deserialization. This vulnerability is uniquely identified as CVE-2023-41330. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in knplabs knp-snappy 1.4.2. Affected by this issue is the function prepareOutput. The manipulation of the argument filename with an unknown input leads to a deserialization vulnerability. Using CWE to declare the problem leads to CWE-502. The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. Impacted is confidentiality, integrity, and availability. CVE summarizes:

knplabs/knp-snappy is a PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page. ## Issue On 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.

The weakness was disclosed 09/07/2023 as GHSA-92rv-4j2h-8mjj. The advisory is available at github.com. This vulnerability is handled as CVE-2023-41330 since 08/28/2023. Technical details are known, but there is no available exploit.

Upgrading to version 1.4.3 eliminates this vulnerability. Applying the patch d3b742d61a68bf93866032c2c0a7f1486128b67e is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• knplabs

Name

• knp-snappy

Version

• 1.4.2

License

• open-source

CPE 2.3info

• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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