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Full vulnerability report · 2026
CVE-2026-5267High confidence

Unauthenticated Event Stream Exposure of Session Tokens in Navigator NCS

Ciena · Navigator NCS

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

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 0.36% for the current model date.

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

  1. Confirm that the asset runs Ciena Navigator NCS and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-87295

No EUVD known-exploited evidence

Ciena Navigator Network Control Suite (NCS) contains an information exposure vulnerability in an event-streaming API that does not properly enforce authentication. An unauthenticated attacker with network access to the affected service could access the event stream and potentially obtain sensitive information.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
7.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Ciena Navigator Network Control Suite (NCS) contains an information exposure vulnerability in an event-streaming API that does not properly enforce authentication. An unauthenticated attacker with network access to the affected service could access the event stream and potentially obtain sensitive information.

What

Ciena Navigator Network Control Suite (NCS) contains an information exposure vulnerability in an event-streaming API that does not properly enforce authentication. An unauthenticated attacker with network access to the affected service could access the event stream and potentially obtain sensitive information.

Why

A security-sensitive function is reachable without the authentication check that should protect it.

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

Ciena Navigator Network Control Suite (NCS) contains an information exposure vulnerability in an event-streaming API that does not properly enforce authentication. An unauthenticated attacker with network access to the affected service could access the event stream and potentially obtain sensitive information.

Why

A security-sensitive function is reachable without the authentication check that should protect it.

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
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

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
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

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 → Missing Authentication for Critical Function → 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
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-306 ↗

CWE-306: Missing Authentication for Critical Function. The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Common Vulnerability Scoring System 3.1: 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.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-306
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-87295Official EUVD mapping

Ciena Navigator Network Control Suite (NCS) contains an information exposure vulnerability in an event-streaming API that does not properly enforce authentication. An unauthenticated attacker with network access to the affected service could access the event stream and potentially obtain sensitive information.

Official EUVD record ↗
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
Navigator NCS: 8.2, 9.1, 7.2-P01 through 7.2-P07, 8.0-P01 through 8.0-P06A, 9.1-P01 through 9.1-P05, 9.2, 7.2 and any older release, 8.1-P01 through 8.1-P06, 9.0, 10.0-P01 through 10.0-P01B, 8.0, 9.0-P01 through 9.0-P05A, 10.0, 8.1, 8.2-P01 through 8.2-P06, 9.2-P01 through 9.2-P02
Fixed
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
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 25 Sept 2026 · Last source change 25 Sept 2026, 20:40 UTC · CWE-306 · Missing Authentication for Critical Function

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-26
European sourceENISA EUVD · EUVD-2026-87295
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. SeveritySeverity changed from Unknown to High.
    Before
    Unknown
    After
    High
    CISA ADP ↗
  2. CVSS scoreCVSS score changed from not recorded to 7.5 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
    Before
    not recorded
    After
    7.5 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
    CISA ADP ↗
  3. ENISA EUVD mappingEUVD-2026-87295 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-87295"}
    ENISA EUVD ↗
  4. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
  5. Vendor guidanceAuthoritative vendor guidance changed: added remediation: ciena.com/product-security.
    Before
    no authoritative guidance recorded
    After
    remediation: ciena.com/product-security
    CNA ↗
  6. Affected versionsThe structured affected or fixed version information changed.
    Before
    Navigator NCS: 7.2 and any older release, 7.2-P01 through 7.2-P07, 8.0, 8.0-P01 through 8.0-P06A, 8.1, 8.1-P01 through 8.1-P06, 8.2, 8.2-P01 through 8.2-P06, 9.0, 9.0-P01 through 9.0-P05A, 9.1, 9.1-P01 through 9.1-P05, 9.2, 9.2-P01 through 9.2-P02, 10.0, 10.0-P01 through 10.0-P01B · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Navigator NCS: 7.2 and any older release, 7.2-P01 through 7.2-P07, 8.0, 8.0-P01 through 8.0-P06A, 8.1, 8.1-P01 through 8.1-P06, 8.2, 8.2-P01 through 8.2-P06, 9.0, 9.0-P01 through 9.0-P05A, 9.1, 9.1-P01 through 9.1-P05, 9.2, 9.2-P01 through 9.2-P02, 10.0, 10.0-P01 through 10.0-P01B · Fixed: Ciena recommends upgrading to the latest available remediated release. For additional details, refer to myciena.com for current software versions, fixes, and security advisories.; Remediation and Fixes:; Products; Remediated Version; Navigator NCS; 8.0-P06B and; later; 8.1-P06A and; 8.2-P07 and; 9.0-P05B and; 9.1-P05A and; 9.2-P02A and
    CNA ↗
  7. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-87295↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
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.
Free version - for non-commercial use only.CVE-2026-5267 · cve.blacktree.nl