TOTOLINK A3300R cstecgi.cgi setDmzCfg buffer overflow

published 2025-10-27 12 mo ago modified 2026-10-08 32 d ago also EUVD-2025-36097

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.8%; EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits: 0; none known

A security vulnerability has been detected in TOTOLINK A3300R 17.0.0cu.557_B20221024. This affects the function setDmzCfg of the file /cgi-bin/cstecgi.cgi. The manipulation of the argument ip leads to buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed publicly and may be used.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 12 mo ago (2025-10-27)

Exploit prediction

0.84% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/noahze01/IoT-vulnerable/blob/main/TOTOLink/A3300R/setDmzCfg.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
CNA	3.0	8.8	CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
CNA	2.0	9.0	AV:N/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR
CNA	4.0	7.4	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/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
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA	2.0	9.0	AV:N/AC:L/Au:S/C:C/I:C/A:C

Affected products

TOTOLINK A3300R

Classification

Weakness

CWE-120 Buffer Copy without Checking Size of Input
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

github.com /noahze01/IoT-vulnerable/blob/main/TOTOLink/A3300R/setDmzCfg.md
exploit, third-party-advisory
vuldb.com /?id.329910
vdb-entry, technical-description, third-party-advisory
vuldb.com /?ctiid.329910
signature, permissions-required, vdb-entry
vuldb.com /?submit.673722
third-party-advisory, vdb-entry
totolink.net /
product

Sources

CVE List CVE-2025-12240
NVD CVE-2025-12240

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