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CVE Record

CVE-2025-40891: HTML injection in in Time Machine functionality in Guardian/CMC before 25.5.0

A Stored HTML Injection vulnerability was discovered in the Time Machine Snapshot Diff functionality due to improper validation of network traffic data. An unauthenticated attacker can send specially crafted network packets at two different times to inject HTML tags into asset attributes across two snapshots. Exploitation requires a victim to use the Time Machine Snapshot Diff feature on those specific snapshots and perform specific GUI actions, at which point the injected HTML renders in their browser, enabling phishing and open redirect attacks. Full XSS exploitation is prevented by input validation and Content Security Policy. Attack complexity is high due to multiple required conditions.

MediumCVSS 4.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

An unauthenticated attacker can place malicious HTML into network data later displayed by Guardian or CMC’s Time Machine Snapshot Diff. A user must compare the attacker-influenced snapshots and take specific interface actions. The result could support phishing or redirects, but supplied evidence says validation and browser policy prevent full cross-site scripting.

Executive priority

Schedule remediation through normal vulnerability-management processes, prioritizing deployments where untrusted traffic is captured and administrators regularly use Snapshot Diff. Emergency response is not indicated by the supplied evidence, but phishing risk within a trusted security interface warrants timely action.

Technical view

CVE-2025-40891 is stored HTML injection caused by improper validation of network traffic data. Crafted packets must influence two snapshots, followed by victim interaction in Snapshot Diff. CVSS 3.1 is 4.7 (medium), with high attack complexity, required user interaction, limited confidentiality and integrity impact, changed scope, and no availability impact.

Likely exposure

Potential exposure is limited to Nozomi Networks Guardian and CMC deployments using affected Time Machine Snapshot Diff functionality. The title identifies versions before 25.5.0, but the bundle’s structured affected-version entries are inconsistent, listing version “0” with default status unaffected. Confirm exact applicability through the vendor advisory and deployed-version inventory.

Exploitation context

Successful exploitation requires unauthenticated crafted network packets at two different times, selection of the corresponding snapshots, and specific victim GUI actions. The stated impact is phishing and open redirects, not full XSS. The CVE is not listed as KEV, and the supplied sources provide no evidence of active exploitation.

Researcher notes

The vulnerable data flow is network traffic into stored snapshot attributes, then HTML rendering during a two-snapshot diff. Required temporal packet placement and GUI interaction produce high complexity. CSP and input validation reportedly block full XSS. Do not infer broader script execution. Exact affected-version boundaries require vendor confirmation because the supplied structured product records conflict with the title.

Mitigation direction

  • Upgrade Guardian and CMC to version 25.5.0 or later, subject to vendor guidance.
  • Review the Nozomi advisory for product-specific upgrade requirements and supported release details.
  • Restrict use of Snapshot Diff until remediation if untrusted network traffic may influence snapshots.
  • Warn operators against following unexpected links or prompts rendered within snapshot comparison views.

Validation and detection

  • Inventory Guardian and CMC versions and identify installations earlier than 25.5.0.
  • Confirm affected-version applicability against the Nozomi advisory because the supplied structured version data conflicts.
  • Determine whether operators use Time Machine Snapshot Diff on attacker-influenced network data.
  • After upgrading, verify the installed release and review vendor guidance for any additional checks.
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-2025-40891 mapping review

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

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.7 (3.1)
Known Exploited
No
Published

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

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
4.7CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N1.62.7Nozomi
2.3CVSS 4.0LowCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N——Nozomi

Vulnerability scoring details

Base CVSS 4.0 score

2.3Low
CVSS 4.0 vector shape for CVE-2025-40891Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

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.