Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.11% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2025-40896High confidence
Lack of TLS certificate validation when connecting Arc to a Guardian or CMC, in Arc before v2.2.0
Nozomi Networks · Arc
6.3MediumCVSS 4.0
Scheduled
Patch availableMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Nozomi Networks Arc and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
NN-2025:18-01 · CSAF 2.0 · revision 1 · finalNozomi NetworksLack of TLS certificate validation when connecting Arc to a Guardian or CMC, in Arc before v2.2.0
The vendor explicitly identifies these products as affected by this CVE.
- Nozomi Networks Arc <2.2.0
- Summary
- The server certificate was not verified when an Arc agent connected to a Guardian or CMC.
- Remediation
- Upgrade Arc to v2.2.0 or later.
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available01
What, why and how
The server certificate was not verified when an Arc agent connected to a Guardian or CMC. A malicious actor could perform a man-in-the-middle attack and intercept the communication between the Arc agent and the Guardian or CMC. This could result in theft of the client token and sensitive information (such as assets and alerts), impersonation of the server, or injection of spoofed data (such as false asset information or vulnerabilities) into the Guardian or CMC.
What
The server certificate was not verified when an Arc agent connected to a Guardian or CMC. A malicious actor could perform a man-in-the-middle attack and intercept the communication between the Arc agent and the Guardian or CMC. This could result in theft of the client token and sensitive information (such as assets and alerts), impersonation of the server, or injection of spoofed data (such as false asset information or vulnerabilities) into the Guardian or CMC.
Why
The product does not validate, or incorrectly validates, a certificate.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may obtain information outside the intended access boundary.
What
The server certificate was not verified when an Arc agent connected to a Guardian or CMC. A malicious actor could perform a man-in-the-middle attack and intercept the communication between the Arc agent and the Guardian or CMC. This could result in theft of the client token and sensitive information (such as assets and alerts), impersonation of the server, or injection of spoofed data (such as false asset information or vulnerabilities) into the Guardian or CMC.
Why
The product does not validate, or incorrectly validates, a certificate.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may obtain information outside the intended access boundary.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Certificate Validation → obtain information outside the intended access boundary
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-295 ↗
CWE-295: Improper Certificate Validation. The product does not validate, or incorrectly validates, a certificate.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCLowVulnerable-system confidentiality: A successful attack can cause a limited loss.VILowVulnerable-system integrity: A successful attack can cause a limited loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- Nozomi Networks Arc <2.2.0
- Action
- Upgrade Arc to v2.2.0 or later.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 4 Mar 2026 · Last source change 4 Mar 2026, 14:11 UTC · CWE-295 · Improper Certificate Validation
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2025-208269
Product sourceVendor CSAF · Nozomi Networks
Remediation sourceVendor CSAF · Nozomi Networks
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Nozomi Networks ↗
- Before
- < 2.2.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- < 2.2.0 · Fixed: Upgrade Arc to v2.2.0 or later.
- Remediation statusRemediation status changed from Awaiting fix to Patch available.Nozomi Networks ↗
- Before
- Awaiting fix
- After
- Patch available
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: security.nozominetworks.com/NN-2025:18-01; removed remediation: cve.mitre.org/cvename.cgi?name=CVE-2025-40896.Nozomi Networks ↗
- Before
- remediation: cve.mitre.org/cvename.cgi?name=CVE-2025-40896
- After
- remediation: security.nozominetworks.com/NN-2025:18-01
CVE published
Fixed release recorded from official guidance
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.