CVE-2026-91831 (CVSS 3.8)

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.

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CVSS v3.1 Score

3.8

LOW

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-93 CWE-93

References

Other References

https://wpscan.com/vulnerability/6cd60f78-f5e2-4b4a-8d50-7d2bc4f981ee/

Frequently Asked Questions

What is CVE-2026-91831? +

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. It has a CVSS v3.1 base score of 3.8 (LOW).

How severe is CVE-2026-91831? +

CVE-2026-91831 has a CVSS v3.1 score of 3.8 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0016, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-91831? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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