CVE-2019-17495 : What You Need to Know

An exploit has been found in Swagger UI versions earlier than 3.23.11, specifically in the Cascading Style Sheets (CSS) injection function. The vulnerability allows attackers to implement the Relative Path Overwrite (RPO) technique, enabling them to extract input field values that are based on CSS. This includes the extraction of a Cross-Site Request Forgery (CSRF) token value. Although this product permits the incorporation of untrusted JSON data from remote servers, it was not previously known that the inclusion of <style>@import within the JSON data could be used as a means of attack.

Understanding CVE-2019-17495

A Cascading Style Sheets (CSS) injection vulnerability in Swagger UI before 3.23.11 allows attackers to use the Relative Path Overwrite (RPO) technique to perform CSS-based input field value exfiltration, such as exfiltration of a CSRF token value. This product intentionally allows the embedding of untrusted JSON data from remote servers, but it was not previously known that <style>@import within the JSON data was a functional attack method.

What is CVE-2019-17495?

The vulnerability in Swagger UI versions earlier than 3.23.11 allows attackers to exploit a CSS injection flaw, enabling them to extract sensitive information like CSRF tokens.

The Impact of CVE-2019-17495

Attackers can perform CSS-based input field value exfiltration, including extracting CSRF token values.
Malicious actors can abuse the <style>@import within JSON data to launch attacks.

Technical Details of CVE-2019-17495

A detailed look at the technical aspects of the vulnerability.

Vulnerability Description

Type: Cascading Style Sheets (CSS) injection
Exploitation: Relative Path Overwrite (RPO) technique
Consequence: Extraction of input field values, including CSRF tokens

Affected Systems and Versions

Systems: Swagger UI versions earlier than 3.23.11
Versions: Specifically affects versions before 3.23.11

Exploitation Mechanism

Attackers exploit the CSS injection flaw to extract sensitive data.
Utilize the RPO technique to exfiltrate input field values.

Mitigation and Prevention

Steps to mitigate the impact of CVE-2019-17495.

Immediate Steps to Take

Update Swagger UI to version 3.23.11 or later.
Monitor and restrict the incorporation of untrusted JSON data.

Long-Term Security Practices

Regularly audit and review CSS injection points in applications.
Educate developers on secure coding practices to prevent CSS vulnerabilities.

Patching and Updates

Apply security patches promptly.
Stay informed about security alerts and updates from Swagger UI.