CVE Catalog

CVE-2026-92537

MediumCVSS 5.3
Published: Updated: Translated: NVD NIST

Summary

The Newsletter plugin for WordPress up to version 9.3.9 has a vulnerability to insufficiently protected credentials. The public click-tracking REST route `/tnp/l/` is registered with `permission_callback => '__return_true'` and upon receiving a valid keyed-MD5 signature, calls `set_user_cookie()`, which emits a `Set-Cookie: newsletter=<id>-<raw_token>` response header to the requester because the subscriber object loaded via `get_user()` lacks the `_trusted` property, causing `get_user_key()` to return the raw token column value instead of its MD5-masked variant.

Risk Assessment

An unauthenticated attacker who obtains a signed click-tracking URL for a subscriber can obtain the victim's permanent raw authentication cookie. They can then export the subscriber's full PII record, modify their stored profile, and silently unsubscribe them without any nonce, password, or email challenge, posing a serious privacy and data integrity risk.

Recommendation

Immediately update the Newsletter plugin to the latest version that fixes this vulnerability. Additionally, restrict access to mail logs and Referer headers, and consider rotating the relink key to invalidate existing signed URLs.

Related vulnerabilities

Original NVD description (English source)

The Newsletter – Send awesome emails from WordPress plugin for WordPress is vulnerable to Insufficiently Protected Credentials in all versions up to, and including, 9.3.9 The plugin's public click-tracking REST route `/tnp/l/` is registered with `permission_callback => '__return_true'` and, upon receiving a valid keyed-MD5 signature, calls `set_user_cookie()`, which emits a `Set-Cookie: newsletter=<id>-<raw_token>` response header to the requester because the subscriber object loaded via `get_user()` lacks the `_trusted` property, causing `get_user_key()` to return the raw token column value instead of its MD5-masked variant. This makes it possible for unauthenticated attackers who obtain any signed click-tracking URL for a target subscriber to receive that subscriber's permanent raw authentication cookie, which they can then use to export the subscriber's full PII record via the JSON profile-export endpoint (`?na=px`), rewrite the subscriber's stored profile (`?na=ps`), and silently unsubscribe the subscriber via the RFC-8058 one-click endpoint (`?na=ocu`), none of which require a nonce, password, or email challenge. Signed tracking URLs are embedded in every external link of every newsletter delivered to a subscriber, carry no timestamp, and never expire until the site's relink key rotates, meaning that any party who observes such a URL — through a forwarded email, a shared inbox, a mail-gateway log, or Referer headers on the redirect target, which has no Referrer-Policy set — can replay it indefinitely to obtain the victim's credential.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS