CVE-2023-41330
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.29%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 2.29% probability · 82th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-502
- Affected
- knplabs/snappy
- Source
- security-advisories@github.com
References
- https://github.com/KnpLabs/snappy/commit/d3b742d61a68bf93866032c2c0a7f1486128b67ePatch
- https://github.com/KnpLabs/snappy/security/advisories/GHSA-92rv-4j2h-8mjjExploit, Mitigation, Vendor Advisory
- https://github.com/KnpLabs/snappy/security/advisories/GHSA-gq6w-q6wh-jggcExploit, Vendor Advisory
- https://github.com/KnpLabs/snappy/commit/d3b742d61a68bf93866032c2c0a7f1486128b67ePatch
- https://github.com/KnpLabs/snappy/security/advisories/GHSA-92rv-4j2h-8mjjExploit, Mitigation, Vendor Advisory
- https://github.com/KnpLabs/snappy/security/advisories/GHSA-gq6w-q6wh-jggcExploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.