TOTOLINK A3300R cstecgi.cgi setDdnsCfg buffer overflow

published 2025-10-27 12 mo ago modified 2026-10-08 31 d ago also EUVD-2025-36098

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 weakness has been identified in TOTOLINK A3300R 17.0.0cu.557_B20221024. The impacted element is the function setDdnsCfg of the file /cgi-bin/cstecgi.cgi. Executing manipulation can lead to buffer overflow. The attack may be performed from remote. The exploit has been made available to the public and could be exploited.

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/setDdnsCfg.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/setDdnsCfg.md
exploit, third-party-advisory
vuldb.com /?id.329909
vdb-entry, technical-description, third-party-advisory
vuldb.com /?ctiid.329909
signature, permissions-required, vdb-entry
vuldb.com /?submit.673721
third-party-advisory, vdb-entry
totolink.net /
product

Sources

CVE List CVE-2025-12239
NVD CVE-2025-12239

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