Stored XSS in UPnP Port Mapping Configuration Interface

luci-app-upnp contains a stored cross-site scripting vulnerability that allows unauthenticated LAN clients to inject JavaScript via UPnP IGD AddPortMapping SOAP requests. Attackers can send malicious HTML in the NewPortMappingDescription field, which miniupnpd stores and luci-app-upnp renders without output encoding, executing the payload when administrators view the UPnP or Status pages.

Casky was already ahead

This CVE exploits attack patterns that Casky's 322matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-61875 is a stored cross-site scripting vulnerability in luci-app-upnp that allows unauthenticated attackers on the local network to inject malicious JavaScript through UPnP IGD SOAP requests. By crafting a malicious AddPortMapping request with JavaScript embedded in the NewPortMappingDescription field, attackers can achieve persistent code execution when network administrators access the UPnP or Status pages. This vulnerability is particularly dangerous because it requires no authentication, affects home and small office routers running OpenWrt with UPnP enabled, and can lead to admin account compromise, lateral network movement, or complete device takeover. The attack surface is significant given UPnP's prevalence in consumer and SMB networking equipment.

Casky's 322 matching security skills leverage Claude AI with extended reasoning to detect the attack patterns underlying this vulnerability by mapping it to MITRE ATT&CK techniques TA0001 (Reconnaissance) and TA0043 (Reconnaissance via network traffic analysis). Practitioners using Casky would identify suspicious indicators such as: unusual SOAP request payloads containing HTML/JavaScript tags in port mapping descriptions, abnormal miniupnpd process behavior correlating with web request logs, stored JavaScript appearing in configuration files or database entries, and anomalous admin session activity following access to the UPnP status page. The platform's skills enable detection of both the initial injection vector (malformed SOAP requests) and post-exploitation behaviors (session hijacking, privilege escalation), helping practitioners correlate network-level indicators with application-level artifacts to confirm compromise and investigate scope.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

322 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-61875.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

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abusing-dpapi-for-credential-access

red teaming · high

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abusing-shadow-credentials-for-privesc

red teaming · high

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MITRE ATT&CK Techniques

TA0001 TA0043

Investigate the attack patterns behind CVE-2026-61875

Casky has 322 skills that investigate the attack patterns behind CVE-2026-61875. Run one and get CVSS-scored findings in 3 minutes.

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