Hermes CTI
← Back to CVEs & Vulnerabilities | Threat Reports
Exploitation Hunt & Detections
Vulnerability Intelligence ⚡ CISA KEV Listed CVSS 8.8 (3.1) EPSS 0.3% (21th %) High (Multi-Source Verified)

CVE-2026-58704

CVE-2026-58704 is a CRITICAL risk security flaw. With a CVSS score of 8.8, it is actively exploited in the wild.

Tech Lead Manager (TLM) Strategic Briefing

Engineering Leadership Context

URGENT OPERATIONAL PRIORITY: CVE-2026-58704 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Active weaponization has been observed in real-world adversary campaigns. Engineering leads must prioritize immediate out-of-band patching or enforce compensating architectural mitigations across all affected systems. Statistical Exploit Likelihood (EPSS): Ranked in the 21.0th percentile globally (30-day weaponization probability: 0.3%). Federal Compliance Due Date: 2026-09-19. Mandated Action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines..

Key Strategic Takeaways
  • CISA KEV Catalog: Actively exploited by threat actors in observed intrusions.
  • CVSS Base Severity: 8.8 (3.1) — Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • EPSS Threat Probability: 0.31% (21.0th percentile globally)
  • CWE Root Cause: CWE-285; CWE-693
Prioritization & Remediation Guidance
  • Emergency Remediation: Apply vendor security updates immediately across all public-facing and internal assets.
  • Telemetry & Threat Sweep: Execute detection queries (KQL/SPL/Sigma) across EDR and firewall logs for exploitation artifacts.
  • Perimeter Isolation: If patching cannot occur immediately, isolate affected services or apply WAF virtual patching rules.

Deep Technical & Root-Cause Analysis

Security Engineering

Vulnerability Analysis for CVE-2026-58704: In Cellular Modem, there is a possible permission bypass due to a logic error in the code. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Root-Cause Flaw Classification: Identified under CWE-285, CWE-693. This flaw typically manifests when software fails to properly constrain inputs, validate boundaries, or manage memory lifetimes. CVSS Metric Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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

Exploitation Mechanics & Attack Progression

4-Phase Exploit Sequence
1

Phase 1 - Attack Surface Discovery & Preconditions: Attacker scans public or internal ingress telemetry to identify reachable instances of the vulnerable service. They enumerate software banners, endpoints, or unauthenticated RPC/HTTP headers to confirm exposure.

2

Phase 2 - Malformed Payload Delivery: Attacker transmits specially crafted network requests or input data targeting CVE-2026-58704 directly to the vulnerable component.

3

Phase 3 - Defect Trigger & Execution: The underlying software logic executes the malicious input without proper boundary checks, granting attacker code execution or unauthorized privileged actions.

4

Phase 4 - Post-Exploitation Movement & Shell Access: The payload spawns an interactive command shell (e.g. bash, sh, powershell.exe, cmd.exe), establishes reverse C2 communication, writes persistent webshells to disk, and executes discovery commands to pivot laterally.

Dedicated Threat Hunt & Movement Detections

Tactical SOC & Threat Hunter Playbook

🔍 Hypothesis & Telemetry Hunt Procedure

› 1. Telemetry Verification (EDR Process Lineage): Query endpoint detection telemetry for web application daemons (e.g. w3wp.exe, nginx, httpd, java, node) spawning shell binaries (cmd.exe, powershell.exe, sh, bash) or utility downloaders (certutil, curl, wget).
› 2. Network Ingress / Egress Inspection: Review reverse proxy, WAF, and firewall logs for anomalous POST/GET requests targeting affected service, followed immediately by unauthorized outbound TCP/UDP connections to external IPs.
› 3. Disk & Webroot Forensics: Scan temporary directories (/tmp/, /var/tmp/, C:\Windows\Temp\) and application webroots for newly dropped webshells, compiled DLLs, or executable scripts created around the timestamp of suspicious requests.
› 4. Session & Identity Auditing: Check authentication and IAM audit logs for newly spawned administrator accounts, service token issuance, or sudden privilege escalation originating from the service host.

⚠️ Lateral Movement & Post-Exploitation Indicators

  • ● Spawning of interactive shells (cmd.exe, powershell.exe, /bin/sh, /bin/bash) from web server or middleware processes
  • ● Outbound network connections initiated from server processes to untrusted external IP addresses on non-standard ports
  • ● Creation of temporary executable artifacts or scripts in %TEMP%, /tmp/, or application document roots
  • ● Execution of system discovery commands (whoami, ipconfig, ifconfig, net user, id, uname -a) by web service accounts
  • ● Attempted persistence via scheduled tasks (schtasks.exe), cron jobs, or registry autorun modifications

🛡️ Production Threat Detection Rules

Ready-to-deploy SIEM / EDR queries
Sigma Rule - CVE-2026-58704 Exploitation & Movement 
title: Exploitation and Post-Exploit Movement - CVE-2026-58704
id: fac432e6-3a4e-50af-97d8-709d29b80517
status: experimental
description: Detects suspicious process execution, child process anomalies, and command interpreter invocation associated with CVE-2026-58704 exploitation.
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    ParentImage|endswith:
      - '\\w3wp.exe'
      - '\\httpd.exe'
      - '\\nginx.exe'
      - '\\java.exe'
      - '\\node.exe'
      - '\\tomcat.exe'
    Image|endswith:
      - '\\cmd.exe'
      - '\\powershell.exe'
      - '\\pwsh.exe'
      - '\\certutil.exe'
      - '\\whoami.exe'
  condition: selection
level: high
tags:
  - attack.execution
  - attack.t1059
  - cve.cve-2026-58704
Splunk SPL - CVE-2026-58704 Process Anomalies 
index=security sourcetype=XmlWinEventLog:Microsoft-Windows-Sysmon/Operational EventCode=1 (ParentImage="*w3wp.exe" OR ParentImage="*httpd.exe" OR ParentImage="*nginx.exe" OR ParentImage="*java.exe" OR ParentImage="*node.exe") (Image="*cmd.exe" OR Image="*powershell.exe" OR Image="*certutil.exe" OR Image="*whoami.exe") | eval cve="CVE-2026-58704" | table _time Computer User ParentImage Image CommandLine cve
Microsoft Sentinel KQL - CVE-2026-58704 Attack Telemetry 
// Microsoft Sentinel KQL - Exploitation Detection for CVE-2026-58704
DeviceProcessEvents
| where InitiatingProcessFileName in~ ('w3wp.exe', 'httpd.exe', 'nginx.exe', 'java.exe', 'node.exe', 'tomcat.exe')
| where FileName in~ ('cmd.exe', 'powershell.exe', 'pwsh.exe', 'sh', 'bash', 'whoami.exe', 'certutil.exe')
| extend AssociatedCVE = 'CVE-2026-58704'
| project TimeGenerated, DeviceName, InitiatingProcessFileName, InitiatingProcessCommandLine, FileName, ProcessCommandLine, AccountName, AssociatedCVE

Authoritative Telemetry & Scoring

National Vulnerability Database NVD 2.0

CVSS Base Score: 8.8

Framework: 3.1

CWE Classification:
  • CWE-285
  • CWE-693
CISA KEV Catalog Exploited

Date Added: 2026-09-16

Federal Due Date: 2026-09-19

Mandated Action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

FIRST EPSS Model v3 Model

Exploit Probability: 0.31%

Global Percentile: 21.0th %

Predicts probability of weaponization in the next 30 days based on real-world threat telemetry.

Correlated Threat Reports

high PUB-2026-023

Google Pixel CVE-2026-58704 exploited in the wild

View Report →