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

No. CVE-2021-25299 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-25299?

CVE-2021-25299 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2021-25299?

CVE-2021-25299 has an EPSS score of 97.71% (100th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2021-25299?

No published fix for CVE-2021-25299 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2021-25299

MEDIUMEPSS 100th pctl

6.1

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

97.71%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

References

Exploit2

Product1

assets.nagios.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-09.