CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:H
AI Score
Confidence
Low
EPSS
Percentile
84.6%
Description Summary The URI validation on dompdf 2.0.1 can be bypassed on SVG parsing by passing tags with uppercase letters. This might leads to arbitrary object unserialize on PHP < 8, through the phar URL wrapper. Details The bug occurs during SVG parsing of tags, in src/Image/Cache.php : if ($type === “svg”) { $parser = xml_parser_create(“utf-8”); xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, false); xml_set_element_handler( $parser, function ($parser, $name, $attributes) use ($options, $parsed_url, $full_url) { if ($name === “image”) { $attributes = array_change_key_case($attributes, CASE_LOWER); This part will try to detect tags in SVG, and will take the href to validate it against the protocolAllowed whitelist. However, the `$name comparison with “image” is case sensitive, which means that such a tag in the SVG will pass : As the tag is named “Image” and not “image”, it will not pass the condition to trigger the check. A correct solution would be to strtolower the $name before the check : if (strtolower($name) === “image”) { PoC Parsing the following SVG file is sufficient to reproduce the vulnerability : Impact An attacker might be able to exploit the vulnerability to call arbitrary URL with arbitrary protocols, if they can provide a SVG file to dompdf. In PHP versions before 8.0.0, it leads to arbitrary unserialize, that will leads at the very least to an arbitrary file deletion, and might leads to remote code execution, depending on classes that are available. References GHSA-3cw5-7cxw-v5qg https://nvd.nist.gov/vuln/detail/CVE-2023-23924 dompdf/dompdf@7558f07 https://github.com/dompdf/dompdf/releases/tag/v2.0.2 https://github.com/FriendsOfPHP/security-advisories/blob/master/dompdf/dompdf/CVE-2023-23924.yaml GHSA-3cw5-7cxw-v5qg
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:H
AI Score
Confidence
Low
EPSS
Percentile
84.6%