Security readout for executives and security teams
Plain-English summary
Older versions of Nagios XI (a popular IT monitoring product) have a flaw in the Core Config Manager that lets an attacker slip malicious script into pop-up dialogs. If a logged-in user views the booby-trapped content, the script runs in their browser and could be used to steal session data or take actions as that user.
Executive priority
Schedule as a routine patching item within the next maintenance window. Not an emergency, but Nagios XI is a privileged operations tool, so an authenticated XSS that hijacks an admin session could meaningfully widen blast radius if abused.
Technical view
The Core Config Manager (CCM) in Nagios XI prior to CCM 3.1.1 / Nagios XI 5.8.2 fails to properly validate or escape user-supplied input rendered inside Overlay modal components, enabling stored or reflected cross-site scripting (CWE-79). Exploitation requires an authenticated user (PR:L) and victim interaction (UI:P) and yields limited confidentiality and integrity impact on a separate security scope (browser context).
Likely exposure
Exposure is limited to organizations running Nagios XI versions earlier than 5.8.2 with CCM accessible to authenticated users. Internet-exposed Nagios XI portals raise the risk; internal-only deployments are lower risk but still vulnerable to insider or compromised-account abuse.
Exploitation context
Not listed in CISA KEV and no public reports of active exploitation are cited in the provided sources. Attack requires authenticated access plus victim interaction with a crafted overlay, which lowers practical mass-exploitation risk but supports targeted account-takeover or privilege-escalation chaining inside Nagios XI.
Researcher notes
CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:P, scope-changed VC:N/VI:N/VA:N, SC:L/SI:L/SA:N) reflects authenticated, user-interaction XSS with no direct impact to the Nagios host. CWE-79 in CCM Overlay modals suggests insufficient output encoding in modal rendering paths. Validate which modal endpoints are affected via the VulnCheck advisory; absence of CPE list and broad "versions:[0]" entry means version coverage should be confirmed against the vendor changelog rather than the CVE record.
Mitigation direction
- Upgrade Nagios XI to 5.8.2 or later (CCM 3.1.1+) per vendor changelog.
- Restrict CCM access to trusted administrators and segment the Nagios XI portal from untrusted networks.
- Enforce least-privilege on Nagios XI accounts and require MFA where supported.
- Apply browser-side defenses: strict Content-Security-Policy and HttpOnly/SameSite session cookies.
- Monitor Nagios XI audit logs for unusual CCM configuration changes by low-privilege accounts.
Validation and detection
- Inventory Nagios XI instances and confirm the installed version against the vendor changelog (target >= 5.8.2).
- Confirm CCM component version is 3.1.1 or later after upgrade.
- Review CCM exposure: check whether the portal is reachable from the internet or untrusted segments.
- Test post-upgrade by reviewing release notes and verifying overlay modals render user input as inert text.
- Audit user accounts with CCM privileges and remove stale or shared credentials.
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-2021-47690 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-ccm-xss-via-overlay-modalsCVE 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.