Security readout for executives and security teams
Plain-English summary
Older versions of Nagios Log Server, a tool many IT teams use to collect system logs, have a flaw on three admin web pages that lets a logged-in user plant malicious scripts. When another user (often an administrator) views the affected page, the script runs in their browser and can hijack their session or trick them into harmful actions.
Executive priority
Schedule a planned upgrade to Nagios Log Server 2024R1 (2.1.6+) within the standard patch cycle. Not an emergency, but treat it as a meaningful hygiene item because the vulnerable pages are used by administrators, and a successful attack could expose admin sessions.
Technical view
CVE-2020-36858 is a stored/reflected cross-site scripting weakness (CWE-79) in Nagios Log Server before version 2.1.6, located in the Create User, Edit User, and Manage Host Lists pages. Insufficient input validation and output escaping allow an authenticated low-privilege user to inject script that executes in a victim's browser session against the application's origin.
Likely exposure
Exposure is limited to organizations running Nagios Log Server installs older than 2.1.6 where the web UI is reachable by users who can be socially engineered into visiting a crafted page. Internet-exposed instances increase risk; segmented internal-only deployments reduce it.
Exploitation context
No public reports of in-the-wild exploitation are cited in the bundle, and the CVE is not in CISA KEV. The CVSS 4.0 vector requires network access, low attacker privileges, and victim user interaction. Impact is bounded to confidentiality and integrity of subsequent systems in the victim's browser session.
Researcher notes
Bundle lists CWE-79 across three specific admin endpoints (Create User, Edit User, Manage Host Lists). CVSS 4.0 5.1 reflects PR:L and UI:P with subsequent-system C/I impact, consistent with classic XSS in an authenticated console. Affected version metadata is sparse (defaultStatus unaffected, versions ["0"]); rely on vendor changelog confirming fix in 2.1.6. No KEV entry, no public PoC cited.
Mitigation direction
- Upgrade Nagios Log Server to version 2.1.6 or later per the vendor changelog.
- Restrict Log Server admin UI access to trusted networks and authenticated administrators only.
- Limit account creation privileges to a small set of vetted administrators.
- Enforce browser hardening such as Content-Security-Policy and HttpOnly session cookies where supported.
- Review vendor security guidance for any additional configuration recommendations tied to this release.
Validation and detection
- Inventory all Nagios Log Server instances and record installed versions.
- Confirm any version below 2.1.6 is upgraded and the affected pages reload cleanly post-update.
- Review web server and audit logs for unexpected script content or unusual edits to user records and host lists.
- Test the Create User, Edit User, and Manage Host Lists pages with benign markers to confirm input is properly escaped.
- Validate that admin UI is not exposed to untrusted networks via external scan.
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-2020-36858 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-log-server-2024r1/CVE reference · release-notes, patch
- https://www.vulncheck.com/advisories/nagios-log-server-xss-via-create-user-edit-user-and-manage-host-lists-pagesCVE 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.