Stored Cross-Site Scripting Vulnerability in Heptabase

Heptabase, developed by Hepta Platforms, Inc., is affected by a stored cross-site scripting (XSS) vulnerability, tracked as CVE-2026-78213. This flaw allows an authenticated remote attacker to inject persistent malicious content into specific pages within the application. When legitimate users interact with or view the maliciously crafted content, the injected arbitrary JavaScript code executes within the context of their active browser session. This could potentially lead to session hijacking, unauthorized actions performed on behalf of the victim, or sensitive information disclosure. The vulnerability exists across all versions of Heptabase. Defenders should note that successful exploitation requires prior authentication by the attacker.

Attack Chain

1. The attacker authenticates to the target Heptabase instance using legitimate credentials.
2. The attacker navigates to a feature or input field that persists user-supplied content to a page viewable by other users.
3. The attacker submits malicious content containing a crafted JavaScript payload (e.g., <script>alert(1)</script>) into the vulnerable input field.
4. The application fails to sanitize or neutralize the input, saving the payload directly into the database.
5. A victimized user navigates to the compromised page or view.
6. The application renders the stored payload within the victim's browser session.
7. The browser executes the attacker's JavaScript code in the context of the victim's session.
8. The attacker achieves their objective, such as session token exfiltration or performing unauthorized actions.

Impact

The vulnerability poses a high risk to organizations utilizing Heptabase, as successful exploitation enables authenticated attackers to execute arbitrary code in the browser sessions of other users. This can lead to the compromise of user accounts, theft of sensitive notes or data stored within the platform, and the potential for lateral movement or further unauthorized activity within the enterprise workspace.

Recommendation

Prioritize patching or updating Heptabase to the latest version as soon as a security update is provided by Hepta Platforms, Inc. In the absence of a patch, implement strict Content Security Policy (CSP) headers to mitigate the impact of XSS attacks by restricting the sources from which scripts can be loaded and executed. Monitor web server logs and application logs for suspicious input patterns that include HTML tags or JavaScript keywords directed at application content fields.