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How CVE-2026-62644 Works
CVE-2026-62644 is an improper authentication vulnerability in the password plugin of Roundcube Webmail. The flaw exists because the plugin does not properly validate the username stored in session data during password change operations.
During a password change request, the system reads the username from the session array instead of re-authenticating the user or verifying that the session username matches the authenticated identity. An attacker who can influence the session data—for example, through a cross-site scripting (XSS) flaw, session fixation, or by exploiting another vector that allows session manipulation—can inject a spoofed username into the session.
When the victim (or the attacker themselves) triggers the password change flow, the password plugin uses the attacker-controlled username from the session to determine which account’s password will be changed. The system does not perform a secondary check to ensure the session username matches the authenticated user. As a result, the attacker can change the password of any valid user account without knowing the current password.
The attack vector is remote and requires the attacker to have some level of access to influence session data—this could be achieved via XSS or by compromising a session token. The vulnerability affects the default password plugin, making all installations of vulnerable versions susceptible. Once exploited, the attacker gains full control of the target email account, enabling email theft, impersonation, and lateral movement within an organization.
The weakness maps to CWE-287 (Improper Authentication) and CWE-290 (Authentication Bypass by Spoofing). The CVSS v3.1 score is 6.4 (Medium) with the vector AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N. The vulnerability is not known to be exploited in the wild (EPSS < 1%) and is not in the CISA KEV catalog. Patches are available in versions 1.6.17 and 1.7.2.
DailyCVE Form
Platform: Roundcube Webmail
Version: <1.6.17, 1.7.x<1.7.2
Vulnerability: Session Username Spoofing
Severity: Medium (CVSS 6.4)
date: 2026-07-14
Prediction: Patch already available
What Undercode Say
Analytics:
- Attack Vector: Remote, requires session influence (e.g., XSS)
- Privileges Required: Low (authenticated user or session access)
- User Interaction: Required (victim must trigger password change)
- Confidentiality Impact: High (full email access)
- Integrity Impact: High (password change, account takeover)
- Availability Impact: None
- Exploitability: Moderate (AC:H, PR:L, UI:R)
- EPSS: <1% (low probability of exploitation)
- CISA KEV: Not listed
- CWE: 287, 290
Bash Commands & Codes:
Check Roundcube version:
Check version via composer composer show roundcube/roundcube | grep versions Check via config file grep -E '^\$config['\''version'\'']' /path/to/roundcube/config/config.inc.php Debian/Ubuntu package version dpkg -l | grep roundcube
Update to patched version:
Using composer (if installed via composer) composer update roundcube/roundcube Debian/Ubuntu (stable trixie) sudo apt update && sudo apt install roundcube=1.6.17+dfsg-0+deb13u1 Manual download wget https://github.com/roundcube/roundcubemail/releases/download/1.6.17/roundcubemail-1.6.17-complete.tar.gz tar -xzf roundcubemail-1.6.17-complete.tar.gz
Nessus plugin detection:
Nessus plugin ID 327029 detects this vulnerability Reference: https://vuldb.com/source_nessus_id/378373
How Exploit
While no public exploit is available, the theoretical exploitation steps are:
1. Inject spoofed username into session: The attacker must find a way to write a malicious username into the session array. This could be achieved via:
– Cross-site scripting (XSS) in Roundcube or a third-party plugin
– Session fixation attacks
– Manipulating session cookies if the application uses insecure session handling
2. Trigger password change flow: The attacker or a victim must navigate to the password change functionality. The password plugin reads the username directly from the session.
3. Bypass authentication: The plugin does not verify that the session username matches the authenticated user, so it accepts the spoofed value.
4. Change target password: The system changes the password for the spoofed username, allowing the attacker to log in as that user.
Example (theoretical):
If an attacker can inject session data via XSS: document.cookie = "roundcube_sessid=..."; // session contains malicious username Then navigate to /?_task=settings&_action=plugin.password The plugin uses the injected username and changes the password.
Protection
- Upgrade to Roundcube Webmail 1.6.17 or 1.7.2 immediately.
- Apply Debian security update DSA-6391-1 (version 1.6.17+dfsg-0+deb13u1).
- Disable or remove any custom or third-party authentication plugins until verified.
- Enforce HTTPS and use secure, HttpOnly session cookies.
- Implement multi-factor authentication (MFA) to add a layer of defense.
- Monitor session management activities for suspicious patterns.
- Use Nessus plugin ID 327029 to detect vulnerable installations.
Impact
- Account takeover: Attackers can fully compromise any user account.
- Data breach: Access to sensitive emails, contacts, and attachments.
- Impersonation: Attackers can send emails as the victim.
- Lateral movement: Compromised email accounts can be used for phishing or further attacks within the organization.
- Reputation damage: Organizations relying on Roundcube for email services face trust erosion.
- No prior password knowledge required: The attack does not require knowing the target’s current password.
- Minimal skill required: Exploitation can be automated, making it attractive for cybercriminals.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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