---
id: "CVE-2026-91831"
kind: "vulnerability"
aliases: ["CVE-2026-91831"]
title: "Subscribe to Comments WordPress plugin: email header injection via sender name"
severity: "low"
cvss: 3.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "self-hosted", "wordpress", "wordpress-plugin"]
not_affected_if: ["no-author-level-users", "plugin-2.3.3-or-later", "plugin-not-installed"]
published_at: "2026-10-19T07:16:32+00:00"
first_seen_at: "2026-10-23T21:57:17+00:00"
updated_at: "2026-10-25T04:43:18+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91831", "first_seen_at": "2026-10-23T21:57:17+00:00"}]
---

# Subscribe to Comments WordPress plugin: email header injection via sender name

The Subscribe to Comments WordPress plugin before 2.3.3 does not strip newline characters from its notification sender-name setting before placing it in email headers. An author-level user can inject extra headers such as a hidden Bcc or a spoofed sender.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed plugin version in the WordPress admin Plugins screen or in `wp plugin get subscribe-to-comments --field=version`
- Confirm whether the plugin is active and whether the sender-name setting is used for notifications

## Fix

- Update the Subscribe to Comments plugin to `2.3.3` or later
- Until updated, restrict Author-level and higher accounts to trusted users only

## Timeline

- 2026-10-23T21:57:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-91831

## From the sources

The Subscribe to Comments WordPress plugin before 2.3.3 does not sanitise newline characters from a notification sender-name setting before using it in e-mail headers, allowing users with Author-level access and above to inject arbitrary e-mail headers, such as a hidden Bcc, and to spoof the sender.

---

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