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CVE Record

CVE-2025-40903: HTML injection in Schedule Restore Archive in Guardian/CMC before 26.1.0

A Stored HTML Injection vulnerability was discovered in the Schedule Restore Archive functionality due to improper validation of an input parameter. An authenticated user with administrative privileges can define a malicious restore schedule containing HTML tags. When a victim views the affected schedule, 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
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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 plant hidden HTML content inside a scheduled restore task. When another user views that schedule, the injected content renders in their browser and can be used for phishing or misleading redirects. Full browser takeover is blocked by existing safeguards, and a fix is available in version 26.1.0.

Executive priority

Schedule a planned upgrade to Guardian/CMC 26.1.0 or later during the next maintenance window and restrict administrative access in the interim.

Technical view

CVE-2025-40903 is a stored HTML injection (CWE-79) in the Schedule Restore Archive feature of Nozomi Networks Guardian and CMC before 26.1.0. An authenticated administrator can submit a schedule name/parameter containing HTML tags that are stored without proper validation and later rendered when another user views the schedule. Existing input validation and CSP prevent full JavaScript execution and direct information disclosure, limiting impact to phishing and open-redirect style abuse.

Likely exposure

Operators of Nozomi Networks Guardian and CMC appliances running versions before 26.1.0 are affected. Because these products are commonly deployed in OT and industrial environments (and referenced by Siemens ProductCERT), exposure typically sits inside operational networks with a limited pool of privileged administrators.

Exploitation context

No public reports of exploitation and the CVE is not listed in CISA KEV. Exploitation requires an authenticated administrator to plant the payload and a second user to view the schedule, so realistic scenarios involve insider misuse or a compromised admin account rather than remote unauthenticated attack.

Researcher notes

CWE-79 stored HTML injection in the Schedule Restore Archive input path. CVSS 3.1 vector AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L (5.9) reflects the high-privilege prerequisite and user-interaction gate. Vendor states CSP and input validation prevent full XSS and direct data exfiltration, so realistic abuse paths are social engineering (phishing lures, deceptive links) rather than session theft. Fixed in Guardian/CMC 26.1.0.

Mitigation direction

  • Upgrade Nozomi Guardian and CMC to version 26.1.0 or later per vendor advisory NN-2026:6-01.
  • Limit administrative accounts on Guardian/CMC to a minimal, trusted set and enforce MFA.
  • Review existing restore schedules for unexpected HTML content and remove suspicious entries.
  • Monitor Siemens ProductCERT SSA-827968 for OEM-specific guidance and patch availability.
  • Maintain the current Content Security Policy configuration, which limits impact to HTML injection rather than full XSS.

Validation and detection

  • Confirm Guardian and CMC versions across the fleet and flag anything below 26.1.0.
  • Audit administrator accounts and recent activity in the Schedule Restore Archive feature.
  • Inspect stored restore schedules for HTML tags or unusual characters in name/parameter fields.
  • After patching, verify the advisory's fixed version is running and that CSP headers remain enforced.
Prepared
Confidence
medium
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

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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.

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cve · low confidence lookup

CVE-2025-40903 mapping review

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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-2025-40903Attack 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.

CWE-79 · source CWE mapping

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.

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