CVE-2026-123959: TOTOLINK CA300-PoE cstecgi.cgi setLanguageCfg buffer overflow

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 10 Nov 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.8%

EPSS score, percentile 58.4 of all scored records. A probability estimated by FIRST, not a report of exploitation.

CISA's SSVC assessment in the CVE record lists exploitation as poc.

How severe?

9.4 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

No patch or vendor advisory is listed in the CVE record. Check totolink's advisories.

A public exploit is linked in the references.

Which versions are affected?

Affected

• 6.2c.884

Versions by product

Source: CISA KEV 2026.11.10, as of 10 Nov 2026; FIRST EPSS, as of 12 Nov 2026; CVE List, as of 12 Nov 2026. About the data.

Description

TOTOLINK CA300-PoE cstecgi.cgi setLanguageCfg buffer overflow

A security flaw has been discovered in TOTOLINK CA300-PoE 6.2c.884. The impacted element is the function setLanguageCfg of the file /cgi-bin/cstecgi.cgi. Performing a manipulation of the argument langType results in buffer overflow. The attack can be initiated remotely. The exploit has been released to the public and may be used for attacks.

Source: CVE List, as of 12 Nov 2026. About the data.

What to do

Advisories and patches

No patch, vendor advisory or mitigation is listed in the CVE record. Check totolink's own security advisories for a fix, and compare your version with the affected versions below.

A public exploit is linked in the references.

This summary is based on the CVE record as of 12 Nov 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Source: CVE List, as of 12 Nov 2026. About the data.

Timeline