CVE-2022-1091 in Safe SVG Plugin
Summary
by MITRE • 04/18/2022
The sanitisation step of the Safe SVG WordPress plugin before 1.9.10 can be bypassed by spoofing the content-type in the POST request to upload a file. Exploiting this vulnerability, an attacker will be able to perform the kinds of attacks that this plugin should prevent (mainly XSS, but depending on further use of uploaded SVG files potentially other XML attacks).
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 04/21/2022
The CVE-2022-1091 vulnerability affects the Safe SVG WordPress plugin version 1.9.10 and earlier, representing a critical security flaw in the plugin's file upload sanitization process. This vulnerability arises from insufficient validation mechanisms that fail to properly verify file content type during the upload process, creating a pathway for malicious actors to circumvent the plugin's intended security protections. The flaw specifically targets the content-type header verification within POST requests, allowing attackers to manipulate the upload process by spoofing the content-type parameter to appear as a legitimate SVG file while actually uploading malicious content.
The technical exploitation of this vulnerability occurs through a simple yet effective method of request manipulation where attackers can modify the content-type header in their upload requests to masquerade malicious files as valid SVG images. This bypass mechanism directly undermines the plugin's core security function which is designed to prevent the upload of potentially dangerous files that could contain cross-site scripting payloads or other XML-based attacks. The vulnerability creates a scenario where the plugin's sanitization logic is effectively neutralized, allowing attackers to upload files that would normally be rejected by the system's validation checks.
The operational impact of this vulnerability extends beyond simple bypass of security measures, as it enables attackers to execute cross-site scripting attacks against users who view the compromised SVG files. This represents a significant risk to WordPress site integrity and user security, particularly when SVG files are embedded in web pages or displayed in contexts where user interaction is possible. Depending on how the uploaded SVG files are subsequently processed and displayed, attackers may also be able to execute other XML-based attacks such as XML external entity attacks or other payload delivery mechanisms that leverage the inherent capabilities of SVG files to execute code.
This vulnerability aligns with CWE-20, which addresses improper input validation, and represents a classic example of how insufficient header validation can create security gaps in web applications. From an attack perspective, this flaw maps to several ATT&CK techniques including T1566 for malicious file delivery and T1059 for command and scripting interpreter usage. The vulnerability demonstrates the critical importance of proper file type validation and content verification in web applications, particularly when dealing with rich media formats that can contain executable code or potentially dangerous markup.
The recommended mitigations for CVE-2022-1091 include immediate upgrading to Safe SVG plugin version 1.9.10 or later, which contains the necessary fixes to properly validate content types and prevent spoofing attacks. Organizations should also implement additional security measures such as restricting file upload capabilities, implementing more robust content validation checks, and monitoring for suspicious upload activities. Network-based detection systems should be configured to monitor for unusual content-type headers in file upload requests, while also ensuring that any uploaded SVG files undergo additional verification processes before being made available to users. The vulnerability underscores the necessity of defense-in-depth strategies that combine multiple layers of security controls to protect against similar bypass techniques.