Security readout for executives and security teams
Plain-English summary
Older versions of Nagios XI, a popular IT monitoring product, contain a flaw in the page used to schedule recurring downtime. A logged-in attacker could plant malicious script that runs in another user's browser when they view the affected page. The risk is mainly account-level mischief inside the monitoring console rather than takeover of monitored systems.
Executive priority
Treat as a routine patch-cycle item unless you run unpatched, legacy Nagios XI exposed to a broad user base. No evidence of active exploitation, but operations and security teams should validate version, restrict console access, and schedule the upgrade in the next maintenance window.
Technical view
CVE-2011-10038 is a cross-site scripting issue (CWE-79) in the recurring downtime script of the Nagios XI web interface, in releases prior to 2011R1.9. Insufficient input validation or output encoding lets an authenticated user supply payloads that execute in a victim's browser session. CVSS v4.0 base score is 5.1 (AV:N/AC:L/PR:L/UI:P), reflecting authenticated access and required user interaction.
Likely exposure
Limited to organizations still running Nagios XI builds older than 2011R1.9 with the web UI reachable by users able to author downtime entries. Modern, patched Nagios XI deployments are not in scope. Internet-exposed legacy instances increase exposure; isolated or upgraded environments are largely unaffected.
Exploitation context
No active exploitation is cited in the source bundle, and the CVE is not listed in CISA KEV. Successful abuse requires an authenticated account in Nagios XI plus a victim interacting with a crafted downtime entry. Impact is browser-context script execution, which can enable session hijack or UI redress against other Nagios XI users.
Researcher notes
Authenticated XSS in the recurring downtime feature; CVSS 4.0 indicates low-privilege, user-interaction-required attack with limited subsequent confidentiality and integrity impact in a separate scope. Sources do not provide payload specifics or PoC. Validate fix by inspecting recurring downtime input handlers in 2011R1.9+ for proper encoding and CSP behavior in the Nagios XI UI.
Mitigation direction
- Upgrade Nagios XI to 2011R1.9 or, preferably, a current supported release per vendor changelog.
- Restrict Nagios XI web UI access to trusted networks via VPN or allowlist.
- Limit downtime-scheduling permissions to the smallest set of trusted operators.
- Review Nagios user accounts and rotate credentials suspected of misuse.
- Apply browser and CSP hardening on the monitoring console where supported by the vendor.
Validation and detection
- Confirm installed Nagios XI version against the vendor changelog threshold of 2011R1.9.
- Inventory Nagios XI instances and identify any reachable from untrusted networks.
- Audit accounts with permission to create or edit recurring downtime entries.
- Review web server and application logs for unusual downtime script parameters or script tags.
- After upgrade, retest the recurring downtime workflow to confirm input is properly encoded.
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-2011-10038 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-recurring-downtime-scriptsCVE 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.