TOTOLINK A3700R cstecgi.cgi setDdnsCfg access control

published 2025-04-16 18 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-11153

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits: 0; none known

A vulnerability was found in TOTOLINK A3700R 9.1.2u.5822_B20200513 and classified as critical. Affected by this issue is the function setDdnsCfg of the file /cgi-bin/cstecgi.cgi. The manipulation leads to improper access controls. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 18 mo ago (2025-04-16)

Exploit prediction

0.64% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

lavender-bicycle-a5a.notion.site https://lavender-bicycle-a5a.notion.site/TOTOLINK-A3700R-setDdnsCfg-1cb53a41781f8001b9c0f345a120e2e7?pvs=4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	6.9	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CNA	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CNA	3.0	5.3	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CNA	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:P/A:N
CNA	4.0	6.9	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/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

Affected products

TOTOLINK A3700R

Classification

Weakness

CWE-284 Improper Access Control
CWE-266 Incorrect Privilege Assignment

References

lavender-bicycle-a5a.notion.site /TOTOLINK-A3700R-setDdnsCfg-1cb53a41781f8001b9c0f345a120e2e7?pvs=4
exploit, third-party-advisory
vuldb.com /?id.304844
vdb-entry, technical-description, third-party-advisory
vuldb.com /?ctiid.304844
signature, permissions-required
vuldb.com /?submit.551298
third-party-advisory, vdb-entry
totolink.net /
product

Sources

CVE List CVE-2025-3666
NVD CVE-2025-3666

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary