EUVD-2026-44106
GHSA-vgq9-7jrx-rfx5
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Network-reachable MSMQ service (AV:N), no user interaction, low-complexity trigger, but requires low privileges (PR:L); use-after-free RCE yields total C/I/A impact within the service scope.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Use after free in Windows Message Queuing allows an authorized attacker to execute code over a network.
AnalysisAI
Remote code execution in the Microsoft Message Queuing (MSMQ) service across Windows 10, Windows 11 (through 26H1), and Windows Server 2012-2025 allows an authorized (PR:L) attacker to run arbitrary code over the network by triggering a use-after-free memory-corruption condition. Microsoft self-reported the flaw and has shipped fixed builds; SSVC rates exploitation as none and EPSS is low (0.48%, 38th percentile), so there is no public exploit identified at time of analysis despite the high 8.8 CVSSv3.1 base score.
Technical ContextAI
The affected component is Windows Message Queuing (MSMQ), an optional Windows messaging middleware that accepts queued messages over the network (typically TCP/1801 and related RPC/HTTP endpoints) via the Message Queuing service (mqsvc.exe). The root cause is CWE-416 (use-after-free): the service dereferences or reuses a heap object after it has been freed, which an attacker can influence to corrupt memory and redirect execution. The CPE and EUVD data confirm this is a first-party Microsoft OS component spanning client SKUs (Windows 10 1607/1809/21H2/22H2, Windows 11 24H2/25H2/26H1) and server SKUs (Server 2012, 2012 R2, 2016, 2019, 2022, 2025 including Server Core installations), meaning any of these builds with the MSMQ feature installed exposes the vulnerable code path.
RemediationAI
Vendor-released patch: install the fixed cumulative build for your SKU (e.g. Windows 11 24H2 10.0.26100.8875, 25H2 10.0.26200.8875, 26H1 10.0.28000.2525; Windows 10 21H2 10.0.19044.7548 / 22H2 10.0.19045.7548; Server 2022 10.0.20348.5386; Server 2025 10.0.26100.33158; Server 2019 10.0.17763.9020; Server 2016 10.0.14393.9339; Server 2012 6.2.9200.26226; Server 2012 R2 6.3.9600.23291) as listed in the MSRC guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50505. Where immediate patching is not possible, the most effective compensating control is to remove or disable the Message Queuing Windows feature on hosts that do not require it, which fully eliminates the vulnerable service but breaks any application that relies on MSMQ. If MSMQ must remain enabled, restrict exposure by blocking inbound MSMQ traffic (TCP 1801 and the MSMQ RPC/HTTP ports) at the host and perimeter firewall and limiting access to trusted management segments only - this reduces reachability but will disrupt legitimate remote queue clients. Because exploitation requires at least low privileges (PR:L), tightening account access and network segmentation around MSMQ hosts further lowers risk until patches are applied.
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External POC / Exploit Code
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