SMTP for Sendinblue – YaySMTP <= 1.2 - Unauthenticated Stored Cross-Site Scripting via Email Logs
Strategic Overview
- Status
- Patched in 1.3
- Affected Plugin
- Brevo SMTP – YaySMTP
- Affected Version
<= 1.2- CVSS
- 7.2High
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2025-0953
At a glance
CVE-2025-0953 is a high-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Brevo SMTP WordPress plugin, affecting versions <= 1.2. It carries a CVSS score of 7.2 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 1.3; sites on affected versions should update now. Disclosed February 2025, reported by Cristian Bejan (cbejan).
Vulnerability Overview
The SMTP for Sendinblue – YaySMTP plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 1.2 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in Brevo SMTP <= 1.2 takes no account at all. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.
Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Brevo SMTP the fix is 1.3: builds <= 1.2 are affected, anything from 1.3 onward is not.
Remediation
Update to version 1.3, or a newer patched version
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Brevo SMTP 1.3 closes this, and updating the plugin is the step that ends it.
- Firewall
- Login Security
- Alerts
External References
Related records
Other vulnerabilities in Brevo SMTP – YaySMTP
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