# CVE-2026-76864: Netcore NR255-V stored XSS in QoS rule handlers

Source: https://junglewise.ai/threats/cve-2026-76864-netcore-nr255-v-stored-xss-in-qos-rule-handlers  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-76864 · Severity: medium · CVSS 4.8 · Published 2026-09-15

The Netcore NR255-V router's Quality of Service (QoS) management feature fails to properly sanitize user input when processing QoS rule names. An attacker with administrative access can inject malicious script code that persists in the device's configuration and executes in the web interface whenever the rules are viewed or modified, potentially compromising administrative sessions and router security settings.

Technologies: [Netcore NR255-V](https://junglewise.ai/threats/technologies/nr255-v). Vendors: [Netcore](https://junglewise.ai/threats/vendors/netcore).

## Quick answers

**Is CVE-2026-76864 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76864 being exploited in the wild.

**How severe is CVE-2026-76864?** Medium severity, with a CVSS score of 4.8, published 15 September 2026.

**Which products and versions are affected?** Netcore NR255-V 1.5.130703.

**Is there a fix for CVE-2026-76864?** 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-2026-76864 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2026-76864?** Check whether you run Netcore NR255-V 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

This is a stored cross-site scripting (XSS) vulnerability in the QoS rule name handling of four CGI handlers: qos_xianz_add_cgi, qos_xianz_show_cgi, qos_filter_add_cgi, and qos_filter_show_cgi. The root cause is insufficient input sanitization before QoS rule names are processed via eval() statements, allowing attackers to inject arbitrary JavaScript code. An authenticated administrator can craft a malicious QoS rule name containing script code that persists in the router's configuration; the injected payload executes whenever the affected handlers process the stored data, affecting any user who subsequently views or manages QoS rules. The attack requires high privileges (administrator role), user interaction (visiting the affected web interface), and network access to the router's management interface. Patches or workarounds have not been explicitly noted in available advisories.

## Affected products

- Netcore NR255-V 1.5.130703

## Timeline

- 2026-09-04: disclosed
- 2026-09-15: advisory

## References

- [https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-qos-stored-xss.md](https://github.com/draw-ctf/netcore-router-public-refs/blob/main/2026.08.19-netcore-nr255v-qos-stored-xss.md)
- [https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-stored-cross-site-scripting-via-unescaped-qos-rule-names](https://www.vulncheck.com/advisories/netcore-nr255-v-1.5.130703-stored-cross-site-scripting-via-unescaped-qos-rule-names)

## Related threats

- [Netcore NR255-V stored cross-site scripting in L7 content management](https://junglewise.ai/threats/cve-2026-92257-netcore-nr255-v-stored-cross-site-scripting-in-l7-content)
- [Netcore NR255-V sensitive information disclosure in VPN configuration handlers](https://junglewise.ai/threats/cve-2026-92256-netcore-nr255-v-sensitive-information-disclosure-in-vpn)
- [Netcore NR255-V out-of-bounds read in filter_arp_put_file.cgi](https://junglewise.ai/threats/cve-2026-92255-netcore-nr255-v-out-of-bounds-read-in-filter-arp-put-file-cgi)
- [Netcore NR255-V stored cross-site scripting in DHCP and ARP hostname fields](https://junglewise.ai/threats/cve-2026-76873-netcore-nr255-v-stored-cross-site-scripting-in-dhcp-and-arp)
- [Netcore NR255-V stored cross-site scripting in DHCP and ACL management](https://junglewise.ai/threats/cve-2026-76872-netcore-nr255-v-stored-cross-site-scripting-in-dhcp-and-acl)