CVE-2026-27627 in karakeep
Summary
by MITRE • 02/25/2026
Karakeep is a elf-hostable bookmark-everything app. In version 0.30.0, when the Reddit metascraper plugin returns `readableContentHtml`, the HTML parsing subprocess uses it directly without running it through DOMPurify. Every other content source in the crawler goes through Readability + DOMPurify, but the Reddit path skips both. Since this content ends up in `dangerouslySetInnerHTML` in the reader view, any malicious HTML in the Reddit response gets executed in the user's browser. Version 0.31.0 contains a patch for this issue.
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Analysis
by VulDB Data Team • 03/11/2026
The vulnerability identified as CVE-2026-27627 resides within the Karakeep bookmarking application, specifically affecting version 0.30.0 where a critical security flaw exists in the Reddit metascraper plugin implementation. This issue represents a severe cross-site scripting vulnerability that arises from inconsistent HTML sanitization practices within the application's content processing pipeline. The flaw demonstrates a clear deviation from established security protocols where the application employs different sanitization approaches for different content sources, creating an exploitable gap in the security model. The vulnerability is classified under CWE-79 as a Cross-Site Scripting (XSS) weakness, specifically manifesting as a failure to sanitize or escape HTML content before rendering it in the user's browser context. The security implications extend beyond simple XSS as they represent a complete bypass of the application's intended security boundaries.
The technical flaw manifests when the Reddit metascraper plugin processes content that includes the `readableContentHtml` field in its response. Unlike all other content sources that undergo a two-step sanitization process involving Readability for content extraction followed by DOMPurify for HTML sanitization, the Reddit path directly utilizes the raw HTML content returned by the plugin. This direct utilization bypasses all security measures that would normally protect against malicious HTML injection, creating a dangerous attack surface where any HTML content returned by the Reddit plugin can be executed directly in the user's browser. The vulnerability is particularly concerning because the processed content ultimately gets rendered through React's `dangerouslySetInnerHTML` attribute, which explicitly instructs the framework to bypass its own HTML sanitization mechanisms and inject content directly into the DOM. This combination of factors creates a perfect storm for XSS exploitation where attackers can inject malicious JavaScript code through the Reddit plugin response that will execute with the privileges and context of the victim user.
The operational impact of this vulnerability extends far beyond simple content manipulation, as it provides attackers with the ability to execute arbitrary code within the context of the user's browser session. This creates potential for session hijacking, credential theft, data exfiltration, and privilege escalation attacks that can compromise the entire user environment. The vulnerability affects all users of the Karakeep application who have the Reddit metascraper plugin enabled, making it a widespread concern that could be exploited at scale. Attackers could craft malicious Reddit posts that, when processed by the Karakeep application, would execute malicious scripts in the user's browser, potentially stealing cookies, modifying content, or redirecting users to malicious sites. This vulnerability directly maps to ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, and T1566 for Phishing, as the attack vector involves injecting malicious JavaScript through content processing. The security implications also extend to potential privilege escalation if the application has access to sensitive user data or system resources, as the executed code would have the same privileges as the user running the application.
The remediation for this vulnerability involves implementing consistent HTML sanitization across all content sources within the Karakeep application, ensuring that the Reddit plugin content undergoes the same Readability and DOMPurify processing as all other content sources. Version 0.31.0 of the application addresses this issue by standardizing the content processing pipeline and ensuring that all HTML content, regardless of its source, passes through the same security validation mechanisms. Organizations should immediately update to version 0.31.0 or later to mitigate this vulnerability, and security teams should conduct thorough audits of their content processing pipelines to identify similar inconsistencies that could lead to other security vulnerabilities. The fix demonstrates the importance of consistent security practices and the principle of least privilege in content processing, where all user-provided content should be treated equally in terms of security validation regardless of its source or origin. This vulnerability serves as a critical reminder of the importance of maintaining consistent security controls across all application components and the potential consequences of security bypasses in content processing systems.