CVE-2023-51540: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kunal Na

Q: How do I fix CVE-2023-51540?

custom 404 pro: upgrade to newer than 3.10.0. Exact commands for each OS are on this page.

Q: Is CVE-2023-51540 being exploited?

CVE-2023-51540 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-2023-51540 affect?

CVE-2023-51540 affects custom 404 pro. Severity is high (CVSS 7.1). Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kunal Nagar Custom 404 Pro allows Stored XSS.This issue affects Custom 404 Pro: from n/a through 3.10.0.

Routine

HIGH 7.1UPGRADE

CVE-2023-51540 is a high-severity flaw (CVSS 7.1) affecting custom 404 pro. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kunal Nagar Custom 404 Pro allows Stored XSS.This issue affects Custom 404 Pro: from n/a through 3.10.0.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 71%)
CISA exploited list	No
Weakness	CWE-79
Published	2024-02-01
Last modified	2026-06-17

Publisher (CNA): Patchstack · Vendor: kunalnagar

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

Am I affected?

Timeline

2024-02-01 11:15 UTCPublished CVE record published
2026-06-17 06:41 UTCUpdated Record last modified

kunalnagar custom 404 pro UPGRADE

Affected: <= 3.10.0

Fixed in: newer than 3.10.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy custom-404-pro || rpm -q custom-404-pro || custom-404-pro --version

2. UPGRADE to newer than 3.10.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade custom-404-pro

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade custom-404-pro

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-2023-51540?

custom 404 pro: upgrade to newer than 3.10.0. Exact commands for each OS are on this page.

Is CVE-2023-51540 being exploited?

CVE-2023-51540 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-2023-51540 affect?

CVE-2023-51540 affects custom 404 pro. Severity is high (CVSS 7.1). Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kunal Nagar Custom 404 Pro allows Stored XSS.This issue affects Custom 404 Pro: from n/a through 3.10.0.

How urgent is CVE-2023-51540?

Priority 32/100. High severity

Related CVEs

CVE-2024-39646 HIGH 7.1 UPGRADE Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kunal Cu
CVE-2023-32740 MEDIUM 5.8 UPGRADE Unauth

References

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