CVE-2021-34658: The Simple Popup Newsletter WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of

Q: How do I fix CVE-2021-34658?

simple popup newsletter: upgrade to newer than 1.4.7. Exact commands for each OS are on this page.

Q: Is CVE-2021-34658 being exploited?

CVE-2021-34658 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-34658 affect?

CVE-2021-34658 affects simple popup newsletter. Severity is medium (CVSS 6.1). The Simple Popup Newsletter WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/simple-popup-newsletter.php file which allows attackers to inject arbitrary web scripts, in version

Q: How urgent is CVE-2021-34658?

Priority 41/100. Public exploit reference

This month

MEDIUM 6.1UPGRADE

CVE-2021-34658 is a medium-severity flaw (CVSS 6.1) affecting simple popup newsletter. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Simple Popup Newsletter WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/simple-popup-newsletter.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.4.7.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-08-16
Last modified	2026-06-17

Publisher (CNA): Wordfence · Vendor: keszites

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-08-16 19:15 UTCPublished CVE record published
2026-06-17 03:56 UTCUpdated Record last modified

keszites simple popup newsletter UPGRADE

Affected: <= 1.4.7

Fixed in: newer than 1.4.7

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy simple-popup-newsletter || rpm -q simple-popup-newsletter || simple-popup-newsletter --version

2. UPGRADE to newer than 1.4.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade simple-popup-newsletter

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade simple-popup-newsletter

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-34658?

simple popup newsletter: upgrade to newer than 1.4.7. Exact commands for each OS are on this page.

Is CVE-2021-34658 being exploited?

CVE-2021-34658 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-34658 affect?

CVE-2021-34658 affects simple popup newsletter. Severity is medium (CVSS 6.1). The Simple Popup Newsletter WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/simple-popup-newsletter.php file which allows attackers to inject arbitrary web scripts, in version

How urgent is CVE-2021-34658?

Priority 41/100. Public exploit reference

Software pages

WordPress vulnerabilities · PHP vulnerabilities

References

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