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Fencer Vulns
medium 6.1

CVE-2021-25299 json

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

published 2021-02-15 5 y ago modified 2026-07-09 4 mo ago also EUVD-2021-12199

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
97.8%
EPSS 97.8% chance of exploitation in 30 days, percentile 99.9%
public exploits
0
none known, plus a Nuclei check

Summary

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.

Exploit prediction

97.76% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Nagios XI 5.7.5 - Cross-Site Scripting nuclei detection template
  • github.com https://github.com/fs0c-sh/nagios-xi-5.7.5-bugs/blob/main/README.md referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/161561/Nagios-XI-5.7.5-Remote-Code-Execution.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.