# CVE-2026-76877: WPML Multilingual CMS authentication bypass via race condition

Source: https://junglewise.ai/threats/cve-2026-76877-the-wpml-multilingual-cms-plugin-for-wordpress-is-vulnerable-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-76877 · Severity: high · CVSS 8.1 · Published 2026-11-10

WPML Multilingual CMS is a WordPress plugin that manages multilingual websites across multiple domains with single sign-on capabilities. An unauthenticated attacker can forge cross-domain sign-in tokens during a window when legitimate users are logging out, gaining unauthorized access to their accounts including administrator accounts.

Vendors: [WPML](https://junglewise.ai/threats/vendors/wpml).

## Quick answers

**Is CVE-2026-76877 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76877 being exploited in the wild.

**How severe is CVE-2026-76877?** High severity, with a CVSS score of 8.1, published 10 November 2026.

**Which products and versions are affected?** WPML Multilingual CMS up to and including 4.9.7.

**Is there a fix for CVE-2026-76877?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-76877 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-76877?** Check whether you run WPML Multilingual CMS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a race condition in the `process_iframe_request` function's language-per-domain SSO handler. The function generates cross-domain sign-in tokens via `wp_create_nonce()` on the logout landing page when session tokens are empty, producing predictable anonymous nonces. An attacker can derive the same token by triggering the logout flow independently and submit it with a forged sign-in status to a secondary domain before the legitimate sign-out iframe completes, within a 60-second race window.

## Affected products

- WPML Multilingual CMS up to and including 4.9.7

## Timeline

- 2026-11-10: disclosed

## Related threats

- [WPML Multilingual CMS reflected cross-site scripting](https://junglewise.ai/threats/cve-2023-54413-wpml-multilingual-cms-plugin-for-wordpress-before-4-6-1-contains)