BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2026
CVE-2026-31984High confidence

DoS through oversized audit log entries in Guardian/CMC before 26.2.0

Nozomi Networks · Guardian

Official source article: Siemens SSA-827968 ↗. Check the applicable product and release in the original source.

8.7HighCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
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 0.51% 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 Nozomi Networks Guardian 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Direct vendor intelligence

Authoritative 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.

2 current
SSA-827968 · CSAF 2.0 · revision 5 · finalSiemens ProductCERTSSA-827968: Vulnerability in Nozomi Guardian/CMC Before V26.2.0 on RUGGEDCOM APE1808 Devices
1 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • RUGGEDCOM APE1808 with Nozomi Guardian/CMC< V26.2.0
Summary
A denial-of-service vulnerability caused by unbounded resource allocation was discovered in the audit logging functionality, due to a missing size limit on input recorded into audit entries. An unauthenticated attacker can submit requests containing excessively large input that is recorded into audit entries, possibly exhausting the available disk space and rendering the system inoperable.
Remediation
Upgrade Nozomi Guardian to v26.2.0. Contact customer support to receive patch and update information
NN-2026:11-01 · CSAF 2.0 · revision 1 · finalNozomi NetworksDoS through oversized audit log entries in Guardian/CMC before 26.2.0
2 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • Nozomi Networks Guardian <26.2.0
  • Nozomi Networks CMC <26.2.0
Summary
A denial-of-service vulnerability caused by unbounded resource allocation was discovered in the audit logging functionality, due to a missing size limit on input recorded into audit entries.
Remediation
Upgrade to v26.2.0 or later.
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-2026-42534

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

A denial-of-service vulnerability caused by unbounded resource allocation was discovered in the audit logging functionality, due to a missing size limit on input recorded into audit entries. An unauthenticated attacker can submit requests containing excessively large input that is recorded into audit entries, possibly exhausting the available disk space and rendering the system inoperable.

What

A denial-of-service vulnerability caused by unbounded resource allocation was discovered in the audit logging functionality, due to a missing size limit on input recorded into audit entries. An unauthenticated attacker can submit requests containing excessively large input that is recorded into audit entries, possibly exhausting the available disk space and rendering the system inoperable.

Why

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

A denial-of-service vulnerability caused by unbounded resource allocation was discovered in the audit logging functionality, due to a missing size limit on input recorded into audit entries. An unauthenticated attacker can submit requests containing excessively large input that is recorded into audit entries, possibly exhausting the available disk space and rendering the system inoperable.

Why

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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 → Allocation of Resources Without Limits or Throttling → cause the confidentiality, integrity or availability impact described by the vendor
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-770 ↗

CWE-770: Allocation of Resources Without Limits or Throttling. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

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:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Common 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.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VAHighVulnerable-system availability: A successful attack can cause a major loss.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
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-770
A

Official authority intelligence

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

JVN iPedia · Japanese · JVNDB-2026-023291Nozomi Networks Inc.のCMC等の複数製品における制限またはスロットリング無しのリソースの割り当てに関する脆弱性

監査ログ機能において、監査エントリに記録される入力のサイズ制限が欠如しているため、リソースの無制限割り当てによるサービス拒否の脆弱性が発見されました。認証されていない攻撃者は、監査エントリに記録される非常に大きな入力を含むリクエストを送信することで、利用可能なディスク容量を使い果たし、システムを動作不能にする可能性があります。

Official advisory ↗
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.
Fix availability varies by product
Affected
RUGGEDCOM APE1808 with Nozomi Guardian/CMC< V26.2.0
Fixed
Upgrade to v26.2.0 or later.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
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 9 Jul 2026 · Last source change 11 Aug 2026, 12:23 UTC · CWE-770 · Allocation of Resources Without Limits or Throttling

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-42534
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD modified after enrichment

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    < 26.2.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    < 26.2.0 · Fixed: Upgrade to v26.2.0 or later.
    Nozomi Networks ↗
  2. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Nozomi Networks ↗
  3. Vendor guidanceAuthoritative vendor guidance changed: added remediation: security.nozominetworks.com/NN-2026:11-01; removed remediation: cve.mitre.org/cvename.cgi?name=CVE-2026-31984.
    Before
    remediation: cve.mitre.org/cvename.cgi?name=CVE-2026-31984
    After
    remediation: security.nozominetworks.com/NN-2026:11-01
    Nozomi Networks ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Mitigation reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-42534↗Vendor CSAF · Siemens ProductCERT · Siemens SSA-827968↗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-2026-31984 · cve.blacktree.nl