satollo Newsletter Plugin up to 9.3.9 on WordPress /tnp/l/ set_user_cookie insufficiently protected credentials

Summaryinfo

A vulnerability was found in satollo Newsletter Plugin up to 9.3.9. It has been declared as critical. The impacted element is the function set_user_cookie of the file /tnp/l/. Executing a manipulation can lead to insufficiently protected credentials. The identification of this vulnerability is CVE-2026-92537. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability has been found in satollo Newsletter Plugin up to 9.3.9 and classified as critical. This vulnerability affects the function set_user_cookie of the file /tnp/l/. The manipulation with an unknown input leads to a insufficiently protected credentials vulnerability. The CWE definition for the vulnerability is CWE-522. The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at wordfence.com. This vulnerability was named CVE-2026-92537 since 09/16/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/01/2026). This vulnerability is assigned to T1552 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-90455). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• WordPress Plugin

Vendor

• satollo

Name

• Newsletter Plugin

Version

• 9.3.0
• 9.3.1
• 9.3.2
• 9.3.3
• 9.3.4
• 9.3.5
• 9.3.6
• 9.3.7
• 9.3.8
• 9.3.9

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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