LiveActive security incident?Get immediate response
CVE Record

CVE-2025-40902: HTML injection in Users in Guardian/CMC before 26.1.0

A Stored HTML Injection vulnerability was discovered in the Users functionality due to improper validation of an input parameter. An authenticated user with administrative privileges can create a malicious user whose username contains HTML tags. When a victim attempts to delete a group containing the affected user, the injected HTML renders in their browser, enabling phishing and possibly open redirect attacks. Full XSS exploitation and direct information disclosure are prevented by the existing input validation and Content Security Policy configuration.

MediumCVSS 5.9Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

A flaw in Nozomi Networks Guardian and CMC lets an administrator secretly plant HTML code inside a username. When another administrator deletes a group containing that user, the hidden code renders in their browser and could be used for phishing or misleading links. It cannot steal data outright, and it requires an already-trusted admin to set it up.

Executive priority

Medium priority. Patch Nozomi Guardian/CMC to 26.1.0 during the next maintenance window and reinforce admin account controls; impact requires an already-privileged insider.

Technical view

CVE-2025-40902 is a stored HTML injection (CWE-79) in the Users functionality of Nozomi Guardian and CMC before 26.1.0. A privileged authenticated user can create a username containing HTML tags that later render in a victim admin's browser during a group deletion workflow. Existing input validation and CSP prevent script execution and direct information disclosure. CVSS 3.1 base score is 5.9 (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L).

Likely exposure

Exposure is limited to organizations running Nozomi Networks Guardian or CMC versions before 26.1.0, typically deployed in OT/ICS monitoring environments. Only accounts with administrative privileges to create users and delete groups are in scope, so the attack surface is narrow and mostly internal.

Exploitation context

No public exploitation, no KEV listing, and no known proof-of-concept cited. Exploitation requires an authenticated administrator to plant the payload and a second victim admin to trigger it by deleting a group. Content Security Policy blocks full XSS and direct data theft, so realistic abuse is limited to phishing lures or open-redirect style trickery.

Researcher notes

Scope is Changed with Low CIA impacts because rendering happens in another user's authenticated admin session, but CSP blocks scripting and exfiltration. Realistic abuse paths are phishing anchors or misleading text injected into the deletion confirmation UI. Requires PR:H and UI:R, so this is an insider or post-compromise scenario rather than an external attack. No KEV, no public PoC, and Siemens co-published an advisory, suggesting shared OT deployments.

Mitigation direction

  • Upgrade Nozomi Networks Guardian and CMC to version 26.1.0 or later per vendor advisory NN-2026:5-01.
  • Review Siemens ProductCERT SSA-827968 for any bundled OT platform guidance and coordinated patch windows.
  • Restrict administrative accounts and enforce least privilege for user and group management functions.
  • Audit existing usernames for HTML tags or unusual characters before performing group deletions.
  • Maintain the shipped Content Security Policy; do not relax CSP directives that mitigate script execution.
  • Enable multi-factor authentication and monitor admin session activity for anomalous user creation events.

Validation and detection

  • Confirm installed Guardian and CMC versions against 26.1.0 across all sensors and central consoles.
  • Query the Users table or admin UI for usernames containing angle brackets or HTML entities.
  • Review audit logs for user-creation and group-deletion events performed by administrative accounts.
  • Verify CSP headers are present and unmodified on the management web interface.
  • Test a controlled upgrade in a lab instance to confirm the group-deletion workflow no longer renders raw HTML.
  • Re-check vendor advisories for updates on affected versions and any additional workarounds.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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 · medium confidence lookup

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 lookup
cve · low confidence lookup

CVE-2025-40902 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.9 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L

Official CVE source material

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.

2CVSS vectors
3Timeline events
2ADP providers
3Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

2 official scores

We 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.

ScoreVersionSeverityVectorExploitImpactSource
5.9CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L1.73.7Nozomi
4.8CVSS 4.0MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L——Nozomi

Vulnerability scoring details

Base CVSS 4.0 score

4.8Medium
CVSS 4.0 vector shape for CVE-2025-40902Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Nozomi NetworksGuardian0unaffected
Nozomi NetworksCMC0unaffected
Weakness

CWE details

CWE-79

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.