Which products and versions are affected by CVE-2021-25299?

Affected: Nagios Xi versions 5.7.5. The full list is in the CVE brief.

Is CVE-2021-25299 being exploited in the wild?

It is not listed in any known-exploited vulnerabilities catalog.

Is CVE-2021-25299 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2021-25299?

No public exploit code is known.

Is there a fix for CVE-2021-25299?

No fixed version is listed yet; check the vendor advisory for mitigations.

How urgently should CVE-2021-25299 be patched?

Brandefense priority: patch immediately, because it is very likely to be exploited soon.

Request A Demo

Vulnerability Intelligence

CVE-2021-25299

Medium

Nagios XI version xi-5.7.5 is affected by cross-site scripting (XSS).

Published Feb 15, 2021 · Updated Jul 9, 2026

Key Facts

Patch immediately

CVE-2021-25299 is a medium-severity vulnerability (CVSS 6.1 v3.1) affecting Nagios Xi.
It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
EPSS estimates a 98% probability of exploitation in the next 30 days.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.

CVSS v3.1

6.1

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

EPSS (30-day exploit likelihood)

98%

Higher than 99.9% of all scored CVEs

Exploited in the wild

No known

Not in a known-exploited catalog

Public exploit code

None known

Get the full CVE-2021-25299 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

Nagios XI version xi-5.7.5 is affected by cross-site scripting (XSS). The vulnerability exists in the file /usr/local/nagiosxi/html/admin/sshterm.php due to improper sanitization of user-controlled input. A maliciously crafted URL, when clicked by an admin user, can be used to steal his/her session cookies or it can be chained with the previous bugs to get one-click remote command execution (RCE) on the Nagios XI server.

Affected Products

1 affected entries in total

Product	Affected versions	Fixed in
Nagios XiNagios	5.7.5	n/a

Timeline

Publicly disclosed
Feb 15, 2021
Last updated
Jul 9, 2026

Weakness Type

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

References

FAQ

Common Questions.

Nagios XI version xi-5.7.5 is affected by cross-site scripting (XSS).
Affected: Nagios Xi versions 5.7.5. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.

Is CVE-2021-25299 Running On Your Attack Surface?

Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.