GHSA-56gj-mvh6-rp75

Опубликовано: 07 фев. 2023

Источник: github

Github: Прошло ревью

CVSS3: 10

Описание

URI validation failure on SVG parsing. Bypass of CVE-2023-23924

Summary

Due to the difference in the attribute parser of Dompdf and php-svg-lib, an attacker can still call arbitrary URLs with arbitrary protocols.

Details

Dompdf parses the href attribute of image tags with the following code:

src/Image/Cache.php line 135-150

function ($parser, $name, $attributes) use ($options, $parsed_url, $full_url) { if (strtolower($name) === "image") { $attributes = array_change_key_case($attributes, CASE_LOWER); $url = $attributes["xlink:href"] ?? $attributes["href"]; if (!empty($url)) { $inner_full_url = Helpers::build_url($parsed_url["protocol"], $parsed_url["host"], $parsed_url["path"], $url); if ($inner_full_url === $full_url) { throw new ImageException("SVG self-reference is not allowed", E_WARNING); } [$resolved_url, $type, $message] = self::resolve_url($url, $parsed_url["protocol"], $parsed_url["host"], $parsed_url["path"], $options); if (!empty($message)) { throw new ImageException("This SVG document references a restricted resource. $message", E_WARNING); } } } },

As you can see from the code snippet above, it respects xlink:href even if href is specified.

$url = $attributes["xlink:href"] ?? $attributes["href"];

However, php-svg-lib, which is later used to parse the svg file, parses the href attribute with the following code:

src/Svg/Tag/Image.php line 51-57

if (isset($attributes['xlink:href'])) { $this->href = $attributes['xlink:href']; } if (isset($attributes['href'])) { $this->href = $attributes['href']; }

Since href is respected if both xlink:href and href is specified, it's possible to bypass the protection on the Dompdf side by providing an empty xlink:href attribute.

Impact

An attacker can exploit the vulnerability to call arbitrary URLs with arbitrary protocols if they provide an SVG file to the Dompdf. In PHP versions before 8.0.0, it leads to arbitrary unserialize, which will lead, at the very least, to arbitrary file deletion and might lead to remote code execution, depending on available classes.

Ссылки

Пакеты

Наименование

dompdf/dompdf

composer

Затронутые версииВерсия исправления

= 2.0.2

2.0.3

EPSS

Процентиль: 89%

0.04401

Низкий

10 Critical

CVSS3

CVE ID

CVE-2023-24813

Дефекты

CWE-436

Связанные уязвимости

CVE-2023-24813

CVSS3: 10

ubuntu

около 3 лет назад

Dompdf is an HTML to PDF converter written in php. Due to the difference in the attribute parser of Dompdf and php-svg-lib, an attacker can still call arbitrary URLs with arbitrary protocols. Dompdf parses the href attribute of `image` tags and respects `xlink:href` even if `href` is specified. However, php-svg-lib, which is later used to parse the svg file, parses the href attribute. Since `href` is respected if both `xlink:href` and `href` is specified, it's possible to bypass the protection on the Dompdf side by providing an empty `xlink:href` attribute. An attacker can exploit the vulnerability to call arbitrary URLs with arbitrary protocols if they provide an SVG file to the Dompdf. In PHP versions before 8.0.0, it leads to arbitrary unserialize, which will lead, at the very least, to arbitrary file deletion and might lead to remote code execution, depending on available classes. This vulnerability has been addressed in commit `95009ea98` which has been included in release vers...

CVE-2023-24813

CVSS3: 10

nvd

около 3 лет назад

CVE-2023-24813

CVSS3: 10

debian

около 3 лет назад

Dompdf is an HTML to PDF converter written in php. Due to the differen ...

BDU:2023-00666

CVSS3: 10

fstec

около 3 лет назад

Уязвимость PHP-библиотеки генерации PDF-документов из HTML-разметки и CSS-стилей Dompdf, связанная с возникновением конфликта интерпретаций, позволяющая нарушителю выполнить произвольный код

EPSS

Процентиль: 89%

0.04401

Низкий

10 Critical

CVSS3

CVE ID

CVE-2023-24813

Дефекты

CWE-436