# CVE-2026-91831: Subscribe to Comments 2.3 - 2.3.2 - Author+ Email Header Injection via From Name Setting

> Authors can inject email headers via the sender name setting, enabling hidden BCCs and sender spoofing in the Subscribe to Comments plugin.

- **Severity:** Low 3.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** GHSA-fwc8-9qp3-8f5c

## What is CVE-2026-91831?

CVE-2026-91831 is a low-severity vulnerability in Unknown Subscribe to Comments, published on 19 Oct 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

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.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences)

## Which versions are affected by CVE-2026-91831?


## How do I fix CVE-2026-91831?

No fix has been published for CVE-2026-91831 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-91831 being exploited?

There is no known exploitation of CVE-2026-91831 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91831 and fix it if it is affected.

What it is: CVE-2026-91831 is a low-severity vulnerability in Unknown Subscribe to Comments, published on 19 Oct 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-91831 in the wild and no public exploit code.

Affected product: Unknown Subscribe to Comments. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-91831/ (Markdown: https://insights.sbomify.com/CVE-2026-91831/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91831
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91831
- OSV: https://osv.dev/vulnerability/CVE-2026-91831

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91831/
Summaries are generated and may contain mistakes; the official description above is the record.