# CVE-2026-5691: Totolink A7100RU command injection in setFirewallType

Source: https://junglewise.ai/threats/cve-2026-5691-totolink-a7100ru-command-injection-in-setfirewalltype  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-06. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-5691 · Severity: high · CVSS 7.3 · Published 2026-04-06

A security vulnerability exists in the Totolink A7100RU home router. This flaw allows a remote attacker to take control of the device by sending a specially crafted request to the router's management interface. Successful exploitation could lead to unauthorized access to the network, interception of data, or a complete shutdown of the device's internet services.

Technologies: [TOTOLINK A7100ru](https://junglewise.ai/threats/technologies/a7100ru). Vendors: [TOTOLINK](https://junglewise.ai/threats/vendors/totolink).

## Quick answers

**Is CVE-2026-5691 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5691 being exploited in the wild.

**How severe is CVE-2026-5691?** High severity, with a CVSS score of 7.3, published 6 April 2026.

**Which products and versions are affected?** TOTOLINK A7100ru 7.4cu.2313_b20191024.

**Is there a fix for CVE-2026-5691?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-5691 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5691?** Check whether you run TOTOLINK A7100ru at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An OS command injection vulnerability exists in the /cgi-bin/cstecgi.cgi component of the Totolink A7100RU router (firmware version 7.4cu.2313_b20191024). The vulnerability is located within the setFirewallType function (specifically sub_42DA2C), where the 'firewallType' parameter is improperly sanitized before being passed to the CsteSystem function and subsequently executed via execv(). A remote, unauthenticated attacker can exploit this by sending a crafted JSON POST request containing shell metacharacters (e.g., backticks) to execute arbitrary commands with system privileges. A public Proof of Concept (PoC) demonstrating the use of 'wget' via this vector has been disclosed.

## Affected products

- Totolink A7100RU 7.4cu.2313_b20191024

## Timeline

- 2026-04-06: disclosed: Vulnerability and PoC publicly disclosed via GitHub and VulDB.
- 2026-04-06: advisory: CVE-2026-5691 published.

## References

- [https://github.com/Litengzheng/vuldb_new/blob/main/A7100RU/vul_189/README.md](https://github.com/Litengzheng/vuldb_new/blob/main/A7100RU/vul_189/README.md)
- [https://vuldb.com/submit/792962](https://vuldb.com/submit/792962)
- [https://vuldb.com/vuln/355518](https://vuldb.com/vuln/355518)
- [https://vuldb.com/vuln/355518/cti](https://vuldb.com/vuln/355518/cti)
- [https://www.totolink.net/](https://www.totolink.net/)

## Related threats

- [Totolink A7100RU command injection in setGameSpeedCfg](https://junglewise.ai/threats/cve-2026-5692-totolink-a7100ru-command-injection-in-setgamespeedcfg)
- [Totolink A7100RU OS command injection in setRemoteCfg](https://junglewise.ai/threats/cve-2026-5690-totolink-a7100ru-os-command-injection-in-setremotecfg)
- [Totolink A7100RU command injection in setNtpCfg](https://junglewise.ai/threats/cve-2026-5689-totolink-a7100ru-command-injection-in-setntpcfg)
- [Totolink A7100RU OS command injection in setDdnsCfg](https://junglewise.ai/threats/cve-2026-5688-totolink-a7100ru-os-command-injection-in-setddnscfg)
- [Totolink A7100RU OS command injection in cstecgi.cgi](https://junglewise.ai/threats/cve-2026-5678-totolink-a7100ru-os-command-injection-in-cstecgi-cgi)