Security readout for executives and security teams
Plain-English summary
Older versions of Nagios XI (before 5.5.7) had a flaw in the MRTG graphing component that let someone who already had a low-level account on the server promote themselves to a much more powerful user. It does not allow a remote attacker to break in from the internet, but once any foothold exists the monitoring server itself can be fully taken over.
Executive priority
Treat as a high-priority hardening item on any unpatched Nagios XI server, especially if multiple users can log in to the monitoring host. It is not an emergency for fully patched estates, but a compromised monitoring server typically has broad visibility into the environment, so closing this gap is worth scheduling promptly.
Technical view
Per the CVE record and VulnCheck advisory, Nagios XI prior to 5.5.7 executes MRTG-related processes or scripts with excessive privileges (CWE-250). A locally authenticated, low-privilege user can leverage writable resources or command paths within the MRTG graphing flow to escalate privileges. CVSS 4.0 vector is AV:L/PR:L with high confidentiality, integrity, and availability impact, indicating local access is required but full host compromise is achievable.
Likely exposure
Limited to organizations still running Nagios XI versions earlier than 5.5.7 where untrusted or low-privileged users can log in to the monitoring host. Internet-facing exposure alone is not sufficient; a local account or chained foothold is required. Most patched and modern Nagios XI deployments are not affected.
Exploitation context
No CISA KEV listing and no public reports of active exploitation in the cited sources. The vulnerability requires local, authenticated access (CVSS AV:L/PR:L), so it is most relevant as a post-compromise escalation primitive on monitoring servers rather than an initial-access vector. Treat as a credible insider or chained-attack risk.
Researcher notes
CWE-250 (Execution with Unnecessary Privileges) in the MRTG graphing path. CVSS 4.0 8.5 with AV:L/AC:L/PR:L/UI:N and high VC/VI/VA points to a local privesc with full system impact. Source bundle does not name the specific vulnerable script or technique; consult VulnCheck advisory and Nagios changelog for fix details. No KEV entry, no published PoC referenced in the bundle.
Mitigation direction
- Upgrade Nagios XI to 5.5.7 or later per the vendor changelog.
- Restrict shell and UI access on Nagios XI hosts to vetted administrators only.
- Audit MRTG-related scripts and directories for unsafe permissions and ownership.
- Segment the monitoring server from general user networks and jump hosts.
- Review vendor guidance for any additional hardening steps specific to MRTG.
Validation and detection
- Confirm installed Nagios XI version against the official changelog (must be >= 5.5.7).
- Inventory which accounts have local or SSH access to Nagios XI hosts.
- Review file permissions on MRTG scripts, configs, and output directories.
- Check authentication, sudo, and process-execution logs on monitoring hosts for anomalies.
- Validate patch deployment via configuration management or asset inventory tooling.
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-250: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2018-25123 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
- High
- CVSS
- 8.5 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/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:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
8.5HighVector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/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-privilege-escalation-via-mrtg-graphing-componentCVE 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.
Execution with Unnecessary Privileges
Execution with Unnecessary Privileges represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.