Attack Vectors

Keep Backup Daily (slug: keep-backup-daily) versions 2.1.2 and earlier are affected by CVE-2026-3577, a Medium-severity Stored Cross-Site Scripting (XSS) issue (CVSS 4.4).

The attack requires an authenticated WordPress user with Administrator-level access (or higher). An attacker can inject a malicious payload into the backup title/alias field via the plugin’s AJAX action (update_kbd_bkup_alias, using the val parameter). The injected script is then stored and can execute later when an admin views affected plugin screens.

Security Weakness

The vulnerability is caused by a combination of insufficient input handling and unsafe output rendering. While the plugin uses sanitize_text_field() when saving, that function removes HTML tags but does not encode double quotes. The stored backup titles are later output in an HTML attribute context without proper escaping (for example, not using esc_attr()), enabling attribute-based script injection.

In practical business terms: a value that looks like “just a title” can become executable content when it is placed back into the admin interface without the correct encoding.

Technical or Business Impacts

Although this issue requires high privileges to exploit, it can still create meaningful business risk—especially in organizations where multiple administrators, agencies, or contractors have admin access.

Potential impacts include:

• Admin session abuse: Malicious scripts can run in an administrator’s browser, potentially enabling actions performed “as the admin” within the WordPress dashboard.

• Unauthorized changes and operational disruption: Attackers could attempt to change site settings, modify content, create new users, or interfere with backup workflows—leading to downtime, brand risk, or delayed recovery during an incident.

• Compliance and audit concerns: XSS that executes in privileged contexts can undermine administrative controls and complicate audit trails, increasing scrutiny for regulated teams (Compliance, Legal, Finance) if it contributes to unauthorized changes or data exposure.

Remediation: Update Keep Backup Daily to version 2.1.3 or a newer patched version. As a short-term risk reducer, review and minimize the number of users with Administrator access, especially third-party accounts, until patching is complete.

Similar Attacks

Cross-Site Scripting remains a common way to execute unauthorized actions in a trusted user’s browser, especially in admin interfaces:

CVE-2020-11022 (jQuery) — XSS vulnerability affecting widely deployed web applications
CVE-2019-11358 (jQuery) — issue that could be leveraged toward XSS in certain implementations
CVE-2026-3577 — Keep Backup Daily Stored XSS (this vulnerability)