CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
18.1%
When parsing SVG images Dompdf performs an initial validation to ensure that paths within the SVG are allowed. One of the validations is that the SVG document does not reference itself. However, a recursive chained using two or more SVG documents is not correctly validated. Depending on the system configuration and attack pattern this could exhaust the memory available to the executing process and/or to the server itself.
php-svg-lib, when run in isolation, does not support SVG references for image
elements. An SVG document can, however, be referenced and Dompdf will run that reference through the same validation. Dompdf currently includes validation to prevent self-referential image
references, but a chained reference is not checked. A malicious actor may thus trigger infinite recursion in the validation process by chaining references between two or more SVG images.
This following sources can be used to bypass validation provided by Dompdf:
recurse.html
<img src>
one.svg
<svg width="200" height="200" xmlns="http://www.w3.org/2000/svg">
<image href="two.svg" />
</svg>
two.svg
<svg width="200" height="200" xmlns="http://www.w3.org/2000/svg">
<image href="one.svg" />
</svg>
When Dompdf parses the above payload, it will crash due after exceeding the allowed execution time or memory usage. An attacker sending multiple request to a system can potentially cause resource exhaustion to the point that the system is unable to handle incoming request.
github.com/dompdf/dompdf
github.com/dompdf/dompdf/blob/v2.0.3/src/Image/Cache.php#L136-L153
github.com/dompdf/dompdf/commit/41cbac16f3cf56affa49f06e8dae66d0eac2b593
github.com/dompdf/dompdf/security/advisories/GHSA-3qx2-6f78-w2j2
github.com/FriendsOfPHP/security-advisories/blob/master/dompdf/dompdf/CVE-2023-50262.yaml
nvd.nist.gov/vuln/detail/CVE-2023-50262
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
18.1%