CVE-2026-1836 Overview
CVE-2026-1836 is a credential storage vulnerability that allows the system to retain username and password values from the login form after submission. An attacker with local access to the platform can navigate back in the browser and retrieve the cached credentials directly from the form fields. The flaw is tracked under CWE-257: Storing Passwords in a Recoverable Format and affects Redmine according to the Incibe Security Notice. Exploitation requires local access and limited user interaction, which constrains the practical attack surface.
Critical Impact
An attacker with local access to a workstation where a user has authenticated to Redmine can recover the user's plaintext credentials from browser history or cached form data.
Affected Products
- Redmine (per Incibe advisory)
- Deployments exposing the standard login form
- Browsers configured to cache form input fields
Discovery Timeline
- 2026-06-12 - CVE-2026-1836 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-1836
Vulnerability Analysis
The login form in the affected Redmine deployment does not prevent the browser from retaining submitted credential values. After a user authenticates, the username and password remain accessible in the rendered form state. An attacker with physical or local session access to the browser can use the back navigation function to return to the login page. The cached field values, including the password, are then visible in the document object model.
The vulnerability falls under [CWE-257], which covers storing passwords in a format that allows recovery. In this case the storage location is the browser session itself rather than a server-side data store. The issue is exploitable only when an attacker reaches an already-authenticated workstation, which limits the threat to shared, kiosk, and insider-access scenarios.
Root Cause
The login form lacks the controls necessary to suppress credential caching. Specifically, the password input does not enforce autocomplete="off" or autocomplete="new-password" semantics, and the form submission does not invalidate the in-memory field state. The application also fails to set response headers that would prevent the browser from restoring the form via back-forward cache restoration.
Attack Vector
An attacker requires local access to an unlocked workstation where a legitimate user has authenticated to Redmine. The attacker opens the browser, navigates to the Redmine login URL, and uses the back button or browser history to return to a previously rendered login page. The password field repopulates with the cached value, which can be revealed by changing the input type from password to text using browser developer tools.
No authentication bypass occurs at the application layer. The disclosure is entirely client-side and depends on browser caching behavior interacting with insecure form attributes.
Detection Methods for CVE-2026-1836
Indicators of Compromise
- Browser developer tool activity on workstations where users authenticate to Redmine, particularly inspection of password input elements.
- Unexpected use of browser back navigation to the Redmine login URL after a successful session.
- Authentication anomalies for accounts whose users share endpoints with other staff.
Detection Strategies
- Inspect the Redmine login page HTML for missing autocomplete="off" attributes on credential fields.
- Audit endpoint browser histories for repeated visits to the Redmine login URL from the same session.
- Correlate Redmine login events with workstation lock state to identify access from unlocked, unattended devices.
Monitoring Recommendations
- Enable verbose authentication logging in Redmine and forward events to a centralized log platform for correlation.
- Monitor for credential reuse patterns where the same account authenticates from a workstation shortly after another user's session.
- Alert on developer tool usage on managed endpoints in environments where this is not expected behavior.
How to Mitigate CVE-2026-1836
Immediate Actions Required
- Apply the Redmine update referenced in the Incibe Security Notice as soon as it is available for your deployment.
- Enforce workstation lock policies so that unattended browsers cannot be accessed by other users.
- Require users to fully close browser sessions after logging out of Redmine on shared endpoints.
Patch Information
Refer to the Incibe Security Notice for the vendor-coordinated fix and supported Redmine versions. The remediation should ensure the login form sets autocomplete="off" on credential inputs and that responses include cache-control headers preventing back-forward cache restoration of authenticated pages.
Workarounds
- Deploy a reverse proxy rule that injects Cache-Control: no-store and Pragma: no-cache headers on the Redmine login endpoint.
- Configure managed browsers via group policy to disable form autofill and password caching for the Redmine domain.
- Enforce single sign-on (SSO) for Redmine so that the native login form is bypassed entirely and credentials are not submitted through the vulnerable page.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
