Security readout for executives and security teams
Plain-English summary
Nagios XI, a popular IT monitoring product, has a flaw in its Views page that lets an attacker plant malicious script in the web interface. If a logged-in user opens a tampered view, the script runs in their browser and could steal session data or trick them into unwanted actions. Versions before 5.4.13 are affected.
Executive priority
Schedule a routine patch cycle within the next maintenance window. This is not an emergency: severity is medium, no known exploitation, and exploitation needs an authenticated insider plus user interaction. Treat as standard hygiene unless your Nagios XI is internet-facing or shared across vendors, in which case prioritize sooner.
Technical view
Nagios XI versions prior to 5.4.13 contain a stored or reflected cross-site scripting weakness (CWE-79) on the Views page due to insufficient input validation and output encoding. An authenticated low-privileged user can inject script that executes in another user's browser session, with passive user interaction required, per the CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:P).
Likely exposure
Organizations running Nagios XI below 5.4.13 with the web UI reachable by multiple operators or exposed beyond a tightly controlled admin network. Internet-exposed Nagios XI portals raise exposure further. The CVE record lists no specific affected version range beyond "prior to 5.4.13" — confirm your installed build against vendor changelog notes.
Exploitation context
No public evidence of active exploitation: this CVE is not in CISA KEV, and the cited sources do not report in-the-wild abuse. Exploitation requires authenticated access (PR:L) and victim interaction (UI:P), which limits drive-by abuse but is realistic in shared monitoring tenants or multi-team Nagios deployments.
Researcher notes
CWE-79 on the Views page; CVSS 4.0 base 5.1 with limited confidentiality, integrity, and availability impact at the subsequent system. Authentication required (PR:L) and victim interaction (UI:P) reduce mass-exploit potential. CVE record is light on technical detail — the VulnCheck advisory is the most actionable third-party reference. No PoC, no KEV listing, and no CISA guidance as of the source bundle.
Mitigation direction
- Upgrade Nagios XI to 5.4.13 or later per the official Nagios changelog.
- Restrict Views page edit rights to trusted operators until patched.
- Place the Nagios XI web UI behind VPN or IP allow-listing, not the public internet.
- Enforce unique sessions and short timeouts to limit token theft impact.
- Review Nagios audit logs for suspicious view content or recent edits.
Validation and detection
- Check the Nagios XI build number in Admin > System Information and compare to 5.4.13.
- Inventory all Nagios XI hosts via asset management and confirm patch state.
- Review VulnCheck advisory and Nagios changelog for exact fix commit and behavior.
- Test in a non-production instance whether the Views page reflects unsanitized input.
- Confirm web application firewall rules log or block script payloads to /nagiosxi views endpoints.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2018-25121 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.1 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
5.1MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.nagios.com/changelog/nagios-xi/CVE reference · release-notes, patch
- https://www.vulncheck.com/advisories/nagios-xi-xss-via-views-pageCVE reference · third-party-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.