CVE-2020-37255: WordPress Time Capsule 1.21.16 Authentication Bypass Vulnerability

Technical summary

The vulnerability is an authentication bypass in WordPress Time Capsule 1.21.16 stemming from improper session validation (CWE-288: Authentication Using a Known Password). The flaw allows unauthenticated attackers to craft a POST request containing the IWP_JSON_PREFIX header, which the application fails to properly validate. By exploiting this malformed header, an attacker can obtain a valid administrator session cookie and gain unauthorized access to the WordPress administrative dashboard without credential submission. The vulnerability requires network access only; no user interaction is needed.

Business impact

A compromised WordPress installation exposes your entire web presence to adversaries. An attacker with admin access can modify site content, inject malware, steal customer data, redirect traffic, harvest email addresses, deploy ransomware payloads, or use your server as a launching point for attacks on third parties. For e-commerce sites, this translates to potential payment card data theft and regulatory fines. Recovery requires forensic investigation, malware removal, credential reset across your organization, and customer notification—all costly and reputationally damaging.

Affected systems

This vulnerability affects WordPress installations running Time Capsule Plugin version 1.21.16. The plugin is commonly used for WordPress backups and site restoration. Any site running the affected version is at risk if the plugin remains unpatched. Sites with public-facing WordPress instances are immediately exposed to unauthenticated attacks.

Exploitability

This vulnerability presents high exploitability risk. The attack requires no authentication, no user interaction, and no complex preconditions—only network access to the target WordPress installation. An attacker can exploit this remotely and automatically with a simple HTTP POST request. The vulnerability is trivial to weaponize, making it a high-priority target for automated scanning and exploitation by commodity malware and opportunistic attackers.

Remediation

Immediately update WordPress Time Capsule to a patched version released after the vulnerability disclosure date of June 20, 2026. Verify the exact patched version against the official plugin repository or vendor advisory. If you are unsure whether your site runs this plugin, search your wp-content/plugins directory for 'time-capsule' or use a WordPress security scanner. After patching, conduct a full site audit for signs of unauthorized access, including reviewing WordPress admin user accounts for unfamiliar entries and checking server logs for suspicious POST requests.

Patch guidance

Access your WordPress admin dashboard and navigate to Plugins → Installed Plugins. Locate WordPress Time Capsule and check the current version against the plugin's official page on wordpress.org. If running version 1.21.16 or earlier, verify that a patched version is available from the vendor. Update through the WordPress admin interface if available, or manually download and reinstall the latest version from the official repository. Test the plugin's core functionality post-update. If automatic updates are not available immediately, consider temporarily deactivating the plugin until a fix is confirmed and deployed.

Detection guidance

Monitor web server logs for POST requests containing the 'IWP_JSON_PREFIX' header directed at your WordPress installation. Check WordPress user administration panels for unexpected administrator accounts created between June 20 and the date you patched. Review WordPress security audit logs (via security plugins like Wordfence or Sucuri) for unauthorized login events or privilege escalation attempts. Implement WordPress activity logging if not already in place. Search session and authentication logs for anomalous admin session cookies issued without corresponding login events.

Why prioritize this

This vulnerability scores 7.5 (HIGH) because it enables unauthenticated remote administrative compromise with no user interaction required and no complex prerequisites. The low attack complexity, widespread use of the Time Capsule plugin, and high confidentiality impact from gaining admin access make this a critical priority. Exploitation is trivial, and impacts are severe. Organizations running this plugin should treat patching as urgent.

Risk score, explained

The CVSS 3.1 score of 7.5 reflects: Network-accessible attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high confidentiality impact (C:H) with no integrity or availability impact (I:N, A:N). The high confidentiality impact derives from the ability to read all site data and configuration. The absence of integrity/availability impact in the CVSS vector does not diminish the threat—an attacker with admin access can perform arbitrary data modification and denial-of-service operations beyond what CVSS directly measures.

Frequently asked questions