CVE-2025-9935: A vulnerability was determined in TOTOLINK N600R 4.3.0cu.7866_B20220506. This vulnerability affects the function sub_4159F8 of the file…

PriorityP270critical9.8CVSS 3.1

AVNACLPRNUINSUCHIHAH

EPSS

3.00%

85.8th percentile

A vulnerability was determined in TOTOLINK N600R 4.3.0cu.7866_B20220506. This vulnerability affects the function sub_4159F8 of the file /web_cste/cgi-bin/cstecgi.cgi. Executing manipulation can lead to command injection. The attack can be executed remotely. The exploit has been publicly disclosed and may be utilized.

Affected

2 ranges

Vendor	Product	Version range	Fixed in
totolink	n600r	—	—
totolink	n600r_firmware	—	—

Detection & IOCsextracted from sources · hover to see the quote

path/web_cste/cgi-bin/cstecgi.cgi↗

path/cgi-bin/cstecgi.cgi

snort

alert http any any -> $HOME_NET any (msg:"ET WEB_SPECIFIC_APPS TOTOLINK N600R cstecgi.cgi langType parameter Command Injection Attempt (CVE-2022-26189, CVE-2025-9935)"; flow:established,to_server; http.method; content:"POST"; http.uri; bsize:20; content:"/cgi-bin/cstecgi.cgi"; http.request_body; content:"|22|topicurl|22 3a|"; content:"|22|setting/setLanguageCfg|22|"; within:30; fast_pattern; content:"|22|langType|22 3a|"; pcre:"/^[^\x26]*?(?:(?:\x3b|%3[Bb])|(?:\x0a|%0[Aa])|(?:\x60|%60)|(?:\x7c|%7[Cc])|(?:\x24|%24))+/R"; reference:url,github.com/doudoudedi/TOTOLINK_N600R_Command_Injection/blob/main/TOTOLINK-N600R-Command-Injection.md; reference:cve,2022-26189; reference:cve,2025-9935; classtype:attempted-admin; sid:2061801; rev:1; metadata:affected_product TOTOLINK, attack_target Networking_Equipment, tls_state plaintext, created_at 2025_04_22, cve CVE_2022_26189, deployment Perimeter, deployment Internal, performance_impact Low, confidence High, signature_severity Major, tag Exploit, updated_at 2025_04_22, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)

→Target HTTP POST requests to /cgi-bin/cstecgi.cgi with a JSON body containing 'topicurl' set to 'setting/setLanguageCfg' and a 'langType' parameter containing shell metacharacters (;, newline, backtick, pipe, $) indicative of command injection.
→The vulnerable function is sub_4159F8 within cstecgi.cgi; exploitation is remote and unauthenticated via the langType parameter of the setLanguageCfg endpoint. ↗
→Exploit traffic is plaintext HTTP (not TLS); deploy detection at perimeter and internal network boundaries.
→MITRE ATT&CK mapping: TA0001 Initial Access / T1190 Exploit Public-Facing Application — prioritize alerting on inbound exploitation attempts against TOTOLINK networking equipment.

·Affected product is TOTOLINK N600R firmware version 4.3.0cu.7866_B20220506 specifically; scope detection to this firmware version to reduce false positives. ↗
·The Snort/Suricata rule (ET sid:2061801) also covers CVE-2022-26189 on the same endpoint; tune or split the rule if per-CVE fidelity is required.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvdv4.05.5MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P

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