CVE-2025-6492 is a vulnerability identified in MarkText, an open-source Markdown editor, specifically affecting versions 0.17.0 and 0.17.1. The flaw resides in the function getRecommendTitleFromMarkdownString within the file marktext/src/main/utils/index.js. The vulnerability is characterized by inefficient regular expression complexity, which can be exploited remotely without requiring authentication or user interaction. This type of vulnerability typically leads to a Regular Expression Denial of Service (ReDoS) attack, where crafted input triggers excessive backtracking in the regex engine, causing high CPU usage and potentially rendering the application unresponsive or crashing it. The CVSS 4.0 score assigned is 6.9 (medium severity), reflecting that the attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges or user interaction required (PR:N, UI:N), and impacts availability to a limited extent (VA:L). There is no impact on confidentiality or integrity. The vulnerability has been publicly disclosed, but no known exploits are currently reported in the wild. Since MarkText is a client-side Markdown editor, the attack surface is primarily on users who open malicious Markdown content or interact with compromised documents, potentially leading to denial of service on their local systems. The lack of patch links suggests that a fix may not yet be available or publicly released at the time of this report.

For European organizations, the impact of CVE-2025-6492 is primarily related to availability disruptions on endpoints where MarkText is used. While MarkText is not typically deployed as a server-side application, its use in professional environments for documentation or note-taking means that targeted ReDoS attacks could disrupt workflows or cause temporary denial of service on user machines. This could be exploited in spear-phishing campaigns delivering malicious Markdown files, leading to productivity loss or potential escalation if combined with other vulnerabilities. However, the absence of confidentiality or integrity impact limits the risk of data breaches directly from this vulnerability. Organizations relying heavily on MarkText for collaborative documentation or software development notes might experience localized disruptions. The medium severity rating indicates that while the vulnerability is non-trivial, it does not pose a critical threat to enterprise-wide operations or sensitive data. Nonetheless, the remote exploitability and lack of required privileges make it a concern for endpoint security teams.

1. Immediate mitigation involves restricting the use of MarkText versions 0.17.0 and 0.17.1 until a patched version is released. Organizations should monitor official MarkText repositories and security advisories for updates addressing this vulnerability. 2. Implement endpoint protection measures that can detect and block anomalous CPU usage patterns indicative of ReDoS attacks. 3. Educate users to avoid opening untrusted or unsolicited Markdown files, especially from external sources or email attachments. 4. Employ network-level controls such as sandboxing or content disarm and reconstruction (CDR) for documents entering the organization to prevent malicious Markdown content from reaching end users. 5. Where feasible, consider alternative Markdown editors with a proven security track record until the vulnerability is resolved. 6. Incorporate regular expression complexity analysis tools in the development lifecycle if internally developing or customizing Markdown processing utilities to prevent similar issues.