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Fencer Intel
critical 9.9

CVE-2026-123957 json

TOTOLINK CA300-PoE cstecgi.cgi setIpQosRules buffer overflow

published 5d ago modified 2d ago also EUVD-2026-118996

cvss
9.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

A vulnerability was determined in TOTOLINK CA300-PoE 6.2c.884. Impacted is the function setIpQosRules of the file /cgi-bin/cstecgi.cgi. This manipulation of the argument ipStart causes buffer overflow. It is possible to initiate the attack remotely. The exploit has been publicly disclosed and may be utilized.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2d ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • lavender-bicycle-a5a.notion.site https://lavender-bicycle-a5a.notion.site/TOTOLINK-CA300-PoE-setIpQosRules-3f953a41781f801195e5e07dfe7488b9?source=copy_link referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.4 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P
CNA 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:P/RL:X/RC:C
CNA 3.0 9.9 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:P/RL:X/RC:C
CNA 2.0 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:C
CNA 4.0 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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 CA300-PoE

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

Sources

Fencer Intel 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.