CVE-2026-61918
MEDIUMCVE-2026-61918 is a medium-severity (CVSS 6.5) Out-of-bounds Read vulnerability in microsoft windows 10 21h2. O3 Security detects and blocks CVE-2026-61918 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
Out-of-bounds read in Remote Desktop Client allows an unauthorized attacker to disclose information over a network.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-61918.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-61918 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 371,256 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Description
Out-of-bounds read in Remote Desktop Client allows an unauthorized attacker to disclose information over a network.
Affected Products
windows 10 21h2microsoftwindows 10 22h2microsoftwindows 10 1607microsoftwindows 10 1809microsoftwindows 11 23h2microsoftwindows 11 24h2microsoftDetection & mitigation playbook
Vendor / applianceDetect
Inventory every microsoft windows 10 21h2 deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the microsoft windows 10 21h2 security patch or hotfix for CVE-2026-61918 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-61918 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-61918. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-61918 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-61918 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.