# CVE-2026-5678: Totolink A7100RU OS command injection in cstecgi.cgi

Source: https://junglewise.ai/threats/cve-2026-5678-totolink-a7100ru-os-command-injection-in-cstecgi-cgi  
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-2026-5678 · Severity: high · CVSS 7.3 · Published 2026-04-06

The Totolink A7100RU router, a device used for home and small office networking, contains a security flaw that allows unauthorized remote users to take control of the device. By sending a specially crafted request to the router's management interface, an attacker can execute system-level commands. This could lead to a complete compromise of the network traffic, unauthorized access to connected devices, or a total service outage.

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

## Quick answers

**Is CVE-2026-5678 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5678 being exploited in the wild.

**How severe is CVE-2026-5678?** 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-2026-5678?** 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-2026-5678 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5678?** 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 Totolink A7100RU router (firmware version 7.4cu.2313_b20191024) within the /cgi-bin/cstecgi.cgi component. The vulnerability is located in the setScheduleCfg function (specifically sub_42E7D8), which fails to properly sanitize the user-provided 'mode' parameter. This parameter is passed to Uci_Set_Str and subsequently formatted into a command string via snprintf before being executed by execv() through the CsteSystem function. A remote, unauthenticated attacker can exploit this by sending a crafted POST request containing shell metacharacters (e.g., backticks) in the 'mode' field to achieve arbitrary code execution. A public proof-of-concept (PoC) demonstrating the use of wget for command execution has been disclosed.

## Affected products

- Totolink A7100RU 7.4cu.2313_b20191024

## Timeline

- 2026-04-06: disclosed
- 2026-04-06: advisory

## References

- [https://github.com/Litengzheng/vuldb_new/blob/main/A7100RU/vul_185/README.md](https://github.com/Litengzheng/vuldb_new/blob/main/A7100RU/vul_185/README.md)
- [https://vuldb.com/submit/792608](https://vuldb.com/submit/792608)
- [https://vuldb.com/vuln/355505](https://vuldb.com/vuln/355505)
- [https://vuldb.com/vuln/355505/cti](https://vuldb.com/vuln/355505/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 command injection in setFirewallType](https://junglewise.ai/threats/cve-2026-5691-totolink-a7100ru-command-injection-in-setfirewalltype)
- [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)