Security readout for executives and security teams
Plain-English summary
OPNsense 19.1 has a reflected cross-site scripting issue in its monit interface. An unauthenticated attacker could trick a user into interacting with crafted input so malicious script runs in that user’s browser. Business impact is mainly session, data, or administrative action exposure if a privileged administrator is targeted.
Executive priority
Treat as a timely maintenance and exposure-reduction item, not an emergency based on current evidence. Prioritize internet-exposed or broadly reachable OPNsense 19.1 systems, especially where administrators use the interface from regular browsing sessions.
Technical view
CVE-2019-25375 is CWE-79 reflected XSS affecting OPNsense 19.1. The reported vector is the monit interface mailserver parameter, reachable by network, with no privileges required but user interaction required. CVSS 3.1 is 6.1, with low confidentiality and integrity impact and no availability impact.
Likely exposure
Exposure is limited to environments running OPNsense 19.1, especially where the relevant administrative or monit interface is reachable by untrusted networks or users. Systems on other versions are not identified as affected in the provided sources.
Exploitation context
A public ExploitDB reference exists, but the source bundle does not show CISA KEV listing or confirmed active exploitation. Successful abuse requires a targeted user interaction and would execute script in the victim’s browser context, not directly compromise the firewall host by itself.
Researcher notes
The evidence identifies OPNsense 19.1 and a reflected XSS in the monit mailserver parameter. Public exploit reference increases validation urgency, but active exploitation is not established. The source bundle names a 19.1.1 release announcement as patch-related; confirm exact fixed version and change notes from OPNsense before closing.
Mitigation direction
- Inventory OPNsense appliances and identify any running version 19.1.
- Review the OPNsense 19.1.1 release announcement and vendor guidance for applicable updates.
- Restrict management and monit interface access to trusted networks only.
- Avoid exposing administrative interfaces to the public internet.
- Educate administrators not to interact with unsolicited links or forms targeting management interfaces.
Validation and detection
- Confirm OPNsense version on each appliance.
- Check whether the monit interface is enabled and network-accessible.
- Verify administrative interfaces are restricted by firewall or access controls.
- Review logs for suspicious requests involving the mailserver parameter.
- Confirm updates or compensating controls are documented.
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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2019-25375 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
- 6.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A: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:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- ExploitDB-46351CVE reference · exploit
- OPNsense Official WebsiteCVE reference · product
- OPNsense 19.1.1 Release AnnouncementCVE reference · patch
- VulnCheck Advisory: OPNsense 19.1 Reflected XSS via monit interfaceCVE 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.