CVE-2025-34037: Linksys Routers E/WAG/WAP/WES/WET/WRT-Series

What it is

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.

Description quoted from the CVE record (assigned by VulnCheck, published 2025-06-24).

Weakness: CWE-78 Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’)

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. 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

CISA assessment (SSVC): CISA assesses that a public proof of concept exists. Automatable: yes. Technical impact: total.

Public exploit evidence (Exploit Observer)

Exploit Observer found 1 Exploit-DB entry and 6 code repositories naming this CVE.

• Exploit-DB 31683

Code repositories that name a CVE are often scanners, copies or fakes, and some are malware. Read the code before running anything.

See all 11 references on Exploit Observer

Live scores

EPSS

0.962
very likely to be attacked soon

VEDAS

0.990
strong exploit evidence

On CISA KEV

Not listed

Detection rule

Nuclei · Suricata

Who is affected

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

How to fix it

Fixed versions stated in the CVE record: 1.0.06, 1.0.05, 2.0.00, 2.1.03, 1.0.04.

How to detect it

Nuclei template (active check)

2025-02-06 UTC - Out-of-Bounds Read

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.

Name and description quoted from the template, written by VEDAS.

The template sends 1 request (GET /tmUnblock.cgi?x=%60echo%20m3ialoamtyia%60); it decides using status, word matchers. Severity in the template: high. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

nuclei -u https://your-host -t CVE-2025-34037.yaml

id: CVE-2025-34037

info:
  name: "2025-02-06 UTC - Out-of-Bounds Read"
  author: vedas-arpsyndicate
  severity: high
  description: |
    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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2025-34037&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=series&match=exact
  classification:
    cvss-score: 10.0
    cve-id: CVE-2025-34037
    cwe-id: CWE-125
  metadata:
    verified: false
    max-request: 1
  tags: cve,cve2025,series,cmd

http:
  - method: GET
    path:
      - "{{BaseURL}}/tmUnblock.cgi?x=%60echo%20m3ialoamtyia%60"
    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "m3ialoamtyia"
      - type: status
        status:
          - 200

CVE-2025-34037.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2025-34037 2025-02-06 UTC - Out-of-Bounds Read. Add them to your Suricata rule set and reload.

alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2025-34037 2025-02-06 UTC - Out-of-Bounds Read"; flow:established,to_server; http.uri; content:"/tmUnblock.cgi"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2025-34037; reference:url,https://www.exploit.observer/?keyword=CVE-2025-34037&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=series&match=exact; sid:1003858; rev:2;)

CVE-2025-34037.rules on GitHub

Advisories on this CVE

• “ClingSTUN” Linux backdoor turns IoT devices into proxy nodes and hides its C2 inside public STUN traffic (full advisory)

References

Exploit code

• https://www.exploit-db.com/exploits/31683 (third-party-advisory, exploit)

Technical analysis and advisories

• https://isc.sans.edu/diary/17633 (technical-description)
• https://vulncheck.com/advisories/linksys-routers-command-injection (third-party-advisory)

Other references

• https://github.com/Jarrettgohxz/CVE-research/tree/main/Linksys/E-series/CVE-2025-34037

Other databases

• CVE record (cve.org)
• NVD
• Exploit Observer

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.