CVE-2026-123960 is a critical (CVSS 3.1: 9.9) buffer overflow in TOTOLINK CA300-PoE firmware 6.2c.884 that can be exploited remotely, and a public exploit is available.
What Is It
The flaw is in the setWanConfig function of /cgi-bin/cstecgi.cgi on the TOTOLINK CA300-PoE. An attacker who manipulates the pppoeUser, priDns, or secDns arguments can trigger a buffer overflow. The weaknesses are classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input).
VulDB, the CNA, published the CVE on 2026-11-07. NVD currently lists its status as "Deferred."
Why It Matters
- Remotely exploitable: The CVSS 3.1 vector is
AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. The attack runs over the network, has low complexity, needs low privileges and needs no user interaction. - Scope changed: Successful exploitation can reach beyond the vulnerable component. Confidentiality, integrity and availability impacts are all rated High.
- Public exploit: The CVE description says the exploit "has been made available to the public and could be used for attacks." The CVSS 4.0 metric rates exploit maturity as Proof-of-Concept.
- Scores: CVSS 3.1 is 9.9 (Critical), CVSS 4.0 is 8.6 (High), and CVSS 2.0 is 9.0 (High).
The CISA KEV catalog does not list this CVE, so the supplied data does not confirm active exploitation in the wild. Because a public exploit exists, this device should still be treated as a priority.
What's Vulnerable
| Vendor | Product | Affected Version |
|---|---|---|
| TOTOLINK | CA300-PoE | 6.2c.884 |
The CNA's CPE entry is cpe:2.3:o:totolink:ca300-poe_firmware:*:*:*:*:*:*:*:*. This wildcard CPE covers the firmware generally, but the only version explicitly marked as affected is 6.2c.884.
Patch Status
The supplied records reference no vendor patch, fixed firmware version or advisory. There is no KEV entry, so CISA has issued no required action or due date. The NVD record links only to TOTOLINK's homepage, not to a specific security bulletin. Organizations running CA300-PoE firmware 6.2c.884 should check TOTOLINK directly for updated firmware and keep watching the references below for remediation guidance.