# CVE-2026-121598: TOTOLINK A950RG stack buffer overflow in wireless configuration

Source: https://junglewise.ai/threats/cve-2026-121598-a-security-vulnerability-has-been-detected-in-totolink-a950rg-4  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-04. Updated: 2026-11-04  
License: CC BY 4.0 with a link back

CVE-2026-121598 · Severity: critical · CVSS 9.9 · Published 2026-11-04

The TOTOLINK A950RG router's wireless configuration handler contains a stack buffer overflow vulnerability that allows an attacker to execute arbitrary code on the device. An unauthenticated attacker with network access can craft a malicious request with an oversized WEP key parameter to corrupt the return address and gain full control of the router, leading to network compromise, data interception, or use as an attack platform.

Technologies: [TOTOLINK A950rg](https://junglewise.ai/threats/technologies/a950rg). Vendors: [TOTOLINK](https://junglewise.ai/threats/vendors/totolink).

## Quick answers

**Is CVE-2026-121598 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121598 being exploited in the wild.

**How severe is CVE-2026-121598?** Critical severity, with a CVSS score of 9.9, published 4 November 2026.

**Which products and versions are affected?** TOTOLINK A950rg 4.1.2cu.5268_B20221104.

**Is there a fix for CVE-2026-121598?** 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-2026-121598 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-121598?** Check whether you run TOTOLINK A950rg 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

The vulnerability exists in the setWiFiBasicConfig function within lib/cste_modules/wireless.so, where the wepkey parameter from a JSON request is copied into a 68-byte stack buffer using strcpy() without length validation. An attacker can send a specially crafted POST request to /cgi-bin/cstecgi.cgi with a wepkey value exceeding 112 bytes to overwrite the saved return address. The target firmware (MIPS32 little-endian, non-PIE, no ASLR, no stack canaries) allows reliable exploitation to arbitrary code execution.

## Affected products

- TOTOLINK A950RG 4.1.2cu.5268_B20221104

## Timeline

- 2026-10-10: disclosed: Vulnerability details published on GitHub
- 2026-11-04: advisory: CVE-2026-121598 published

## References

- [https://gist.github.com/H3rmesk1t/e283a4f3224cbd0a57d4392de60bd2c6](https://gist.github.com/H3rmesk1t/e283a4f3224cbd0a57d4392de60bd2c6)
- [https://vuldb.com/cve/CVE-2026-121598](https://vuldb.com/cve/CVE-2026-121598)

## Related threats

- [TOTOLINK A950RG stack buffer overflow in MAC filter handler](https://junglewise.ai/threats/cve-2026-121600-a-flaw-has-been-found-in-totolink-a950rg-4-1-2cu-5268-b20221104)
- [TOTOLINK A950RG stack buffer overflow in WiFi configuration](https://junglewise.ai/threats/cve-2026-121599-a-vulnerability-was-detected-in-totolink-a950rg-4-1-2cu-5268)
- [TOTOLINK A950RG stack buffer overflow in Easy Setup Wizard](https://junglewise.ai/threats/cve-2026-121597-a-weakness-has-been-identified-in-totolink-a950rg-4-1-2cu-5268)
- [TOTOLINK A950RG stack buffer overflow in infostat.cgi](https://junglewise.ai/threats/cve-2026-116508-a-security-flaw-has-been-discovered-in-totolink-a950rg-4-1-2cu)
- [TOTOLINK A950RG information disclosure in getLanguageCfg](https://junglewise.ai/threats/cve-2026-116507-a-vulnerability-was-identified-in-totolink-a950rg-4-1-2cu-5268)