Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2025-34037

E4200 Command Injection

Linksys / E4200 · affected before 1.0.06

Watch CVE-2025-34037 Browse KEV feed
Severity
CVSS 10.0 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
92.8%
First observed
03 Jul 2026
Last observed
10 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2025-34037 is an unauthenticated vulnerability affecting Linksys E4200 and 10 other products. An OS command injection vulnerability exists in various models of E-Series Linksys routers via the /tmUnblock.cgi and...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Also confirmed by third-party sources.

Who is affected?

Linksys / E4200 affected before 1.0.06.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

E4200 Command Injection

An OS command injection vulnerability exists in various models of E-Series Linksys routers via the /tmUnblock.cgi and /hndUnblock.cgi endpoints over HTTP on port 8080. The CGI scripts improperly process user-supplied input passed to the ttcp_ip parameter without sanitization, allowing unauthenticated attackers to inject shell commands.

This vulnerability was reported to be exploited in the wild by the "TheMoon" worm  in 2014 to deploy a MIPS ELF payload, enabling arbitrary code execution on the router. Additionally, this vulnerability may affect other Linksys products to include, but not limited to, WAG/WAP/WES/WET/WRT-series router models and Wireless-N access points and routers. Exploitation evidence was observed by the Shadowserver Foundation on 2025-02-06 UTC.

Linksys Affected
E4200
Before 1.0.06
Linksys Affected
E3200
Before 1.0.05
Linksys Affected
E3000
Before 1.0.06
Linksys Affected
E2500 v1/v2
Before 2.0.00
Linksys Affected
E2100L v1
Through 1.0.05
Linksys Affected
E2000
0
Linksys Affected
E1550
Through 1.0.03
Linksys Affected
E1500 v1
Before 1.0.06
Linksys Affected
E1200 v1
Through 1.0.04
Linksys Affected
E1000 v1
Before 2.1.03
Linksys Affected
E900 v1
Before 1.0.04
View vendor advisory (opens in new tab)
Published
24 Jun 2025
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

edge

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 07 Jul 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
The Shadowserver First 2026-05-28 00:00 UTC
Previdian Sensors 2026-08-06 12:51 UTC
The Hacker News 2026-10-05 15:33 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

9

Attempts observed

6

Unique attacker IPs

4

Attacker countries

CN · DE · IN · NL

3

Sensors observed

CVE-2025-34037 exploitation attempts over the last 80 days

Daily events observed by Previdian sensors

Updated 23 Oct 2026

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5 Aug 21 Aug 6 Sep 22 Sep 23 Oct

First observed 03 Jul 2026 · Last observed 10 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
1
1
5

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

Previdian virtual patch guidance is available for this CVE.

AWS WAF Cloudflare ModSecurity

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Virtual Patch Detail

Compensating WAF rules for this CVE.

Available

Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to Previdian Enterprise users.

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Risk and context

Severity, weaknesses, and research context

CVSS v4.0

10.0 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

EPSS

92.8%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') CWE-78

Recent mention · The Hacker News

Realtek Jungle SDK Exploit Attempts Deliver Cling Botnet With STUN-Based C2

Ravie LakshmananOct 05, 2026Vulnerability / Malware Threat actors have been observed attempting to exploit a now-patched critical security flaw impacting the Realtek Jungle software development kit (SDK) to deploy a botnet malware called Cling. "Cling is notable not because...

Read full advisory

Timeline

From disclosure to observed exploitation

  1. 20:18 UTC

    Virtual patch available

    Compensating WAF rule available to block exploitation

  2. 15:33 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  3. 16:17 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  4. 19:32 UTC

    Indicators of compromise added (12)

    Indicators of compromise recorded

  5. 00:00 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  6. 01:03 UTC

    CVE published

    Vulnerability disclosed publicly

  7. 19:15 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2025-34037

Sample API response 
{
  "cve_id": "CVE-2025-34037",
  "confidence": "Confirmed",
  "cvss_score": 10.0,
  "cvss_estimated": false,
  "epss_score": 0.92774,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 9, "sensors": 3 }
}