CVE-2026-66046 — CVSS 7.5 HIGH Severity | NVD Vulnerability Record

ANALYST: BIVASH KUMAR NAYAK (CHIEF SECURITY ARCHITECT) • PUBLISHED: Tuesday, 18 August 2026
CVE-2026-66046 — CVSS 7.5 HIGH Severity | NVD Vulnerability Record
■ Executive Risk Command Center
CVE ID
CVE-2026-66046
CVSS Score
7.5
HIGH
CISA KEV
Not Listed
Not present in the verified catalog snapshot; this does not prove absence of exploitation

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🔍 CVE-2026-66046  |  ⚠ CVSS 7.5  |  📅 August 18, 2026  |  📂 Vulnerabilities  |  🛡 CYBERDUDEBIVASH®
CVE VULNERABILITY ADVISORY · HIGH
CDB-CTI-2026-E09E55758751 · Generated 2026-08-18T16:08:14.198624Z
Executive Summary

Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options. CVSS Score: 7.5 CWE: CWE-407

Decision: Validate relevance and exposure using the cited source and internal evidence before treating this record as an incident, confirmed compromise, or customer-specific finding.

Threat Classification and Evidence Status
Intelligence family
CVE Vulnerability Advisory
Technical severity
HIGH
Exploitation
Not confirmed by available evidence; not in verified KEV snapshot
Patch/remediation
Availability not established in the source record — verify vendor guidance
Verified Facts
Source type: CVE Vulnerability Advisory
Source publication time: 2026-08-18T15:16:57
CVE: CVE-2026-66046
CVSS base score: 7.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-407
KEV catalog check: Not present in the successfully retrieved catalog snapshot; this does not prove absence of exploitation.
Technical Analysis

Vulnerability class: Denial Of Service. Assessment: Active exploitation is not confirmed by the available evidence. Prioritization must combine technical severity, exposure, asset criticality, and compensating controls.

Exposure and Remediation Decisions
P0 — Inventory: Confirm the affected product and version against authoritative vendor/NVD data; prioritize internet-facing and business-critical assets.
P0 — Remediation: Availability not established in the source record — verify vendor guidance
P1 — Compensating controls: Restrict exposure, enforce least privilege, and apply vendor-supported mitigations when immediate remediation is not possible.
P1 — Retrospective review: Search only the telemetry relevant to the affected component and validated vulnerability class; absence of alerts does not prove absence of exploitation.
Source Evidence Extract
CVE ID: CVE-2026-66046
Description: Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.
CVSS Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWEs: CWE-407

This extract is escaped and rendered from the ingested source record; generated analysis is not presented as a source fact.

MITRE ATT&CK Mapping
Impact → Endpoint Denial of Service (T1499), only where service exhaustion is observed.
Mappings are conditional analytical aids, not claims that the technique occurred. Promote a mapping to observed only after telemetry confirms the behavior.
Detection Engineering
DETECTION STATUS: TELEMETRY_SPECIFICATION_ONLY

Availability-impact evidence does not justify a process-execution or web-shell rule.

Alert on affected-service crash/restart loops, saturation, latency, and request-rate anomalies against a measured baseline.
Correlate load-balancer, application, operating-system, and infrastructure metrics around the reported failure window.
References
Automated intelligence synthesis — not human reviewed. Public reference draft — not a certified customer deliverable. Customer-specific action requires exposure validation and accountable human approval.
Role-Based Decisions
Vulnerability Manager: Track against cve vulnerability advisory intake. Exploitation status: Not confirmed by available evidence; not in verified KEV snapshot. Patch status: Availability not established in the source record — verify vendor guidance. — Prioritization reflects this record's own exploitation/patch evidence, not a fixed severity template.
SOC Manager: Review the detection guidance below before enabling any blocking action on it. — Detection maturity for this record is stated explicitly, not assumed production-ready.
Source Reliability & Corroboration

nvd: A/B — Reliable (completely or usually reliable source)

Whether an independent second source corroborates this record has not been assessed (see the evidence ledger). This report does not wait on that assessment to publish, and does not overstate certainty in the meantime.

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Contact: bivash@cyberdudebivash.com · Website: https://cyberdudebivash.com
Intelligence source: https://nvd.nist.gov/vuln/detail/CVE-2026-66046 · CYBERDUDEBIVASH® SENTINEL APEX Evidence Engine v3.0
Provenance and Review Status
Report IDCDB-CTI-2026-E09E55758751
Source systemnvd
Source published2026-08-18T15:16:57
Source-record SHA-256e09e55758751ca499b69491b03c3e03b46f1633901be3cc032ab8fdad30ffe37
Generated UTC2026-08-18T16:08:14.205131Z
Review statusAutomated intelligence synthesis — not human reviewed
CertificationPublic Intelligence Certification: TACTICAL_READY (automated evidence-graph certification — see Provenance for the source basis)