EUVD-2026-43797
GHSA-c3wc-3frp-jhmq
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Local-only attack requiring an existing low-privileged session and symlink creation ability; impact is read-only file disclosure with no integrity or availability consequence.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
2DescriptionNVD
Improper link resolution before file access ('link following') in Universal Plug and Play (upnp.dll) allows an authorized attacker to disclose information locally.
AnalysisAI
Link-following vulnerability in Windows upnp.dll (Universal Plug and Play) enables a locally authenticated attacker with standard user privileges to read files outside intended access boundaries by planting symbolic links or junction points that the service resolves without proper validation. Affected scope spans Windows 10 (versions 1607-22H2), Windows 11 (versions 24H2-26H1), and Windows Server 2012 through 2025. No public exploit has been identified at time of analysis; EPSS of 0.27% (19th percentile) and CISA SSVC exploitation status of 'none' collectively indicate low near-term exploitation probability.
Technical ContextAI
CWE-59 (Improper Link Resolution Before File Access / Link Following) arises when a privileged process resolves symbolic links, hard links, or NTFS junction points without verifying that the resolved target falls within an authorized path. The vulnerable component is upnp.dll, Microsoft's implementation of the Universal Plug and Play protocol stack, which runs as a privileged Windows service. When upnp.dll performs file system operations - such as reading configuration or device description files - it follows attacker-controlled links to unintended targets, effectively lending its elevated read access to a low-privileged caller. CPE data confirms the flaw spans the application-layer UPnP stack across every currently supported Windows 10, Windows 11, and Windows Server release from 2012 onward.
RemediationAI
Apply the Microsoft security update addressing CVE-2026-49180, available via Windows Update and WSUS; exact fixed builds per platform are listed in the affected products section above. The vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49180 provides patch-specific guidance and patch Tuesday deployment notes. If immediate patching is infeasible, restrict local user logon rights to the affected systems - particularly preventing untrusted users from obtaining interactive sessions - since the attack requires PR:L local access. Additionally, auditing SeCreateSymbolicLinkPrivilege assignments and enforcing the 'Developer Mode' symlink restriction via Group Policy (enabling 'Create symbolic links' only for administrators) narrows the set of principals capable of planting the malicious link, though this is a compensating control rather than a fix. Note that disabling the UPnP service (svchost-hosted SSDPSRV and upnphost) is an option in environments that do not rely on UPnP device discovery, but this may disrupt network printer and media device detection.
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Same weakness CWE-59 – Improper Link Resolution Before File Access
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External POC / Exploit Code
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