Your RSA-2048 keys break in 2030. Find every one of them before attackers do.
🛡️
Not in CISA KEV
CRITICAL severity

CVE-2026-54990

CRITICAL

CVE-2026-54990 is a critical-severity (CVSS 9.8) CWE-122 vulnerability in microsoft windows 11 24h2. O3 Security detects and blocks CVE-2026-54990 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.

Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.

Published
Jul 14, 2026
Updated
Jul 22, 2026
Affected
4 products
Patched
See advisory
Exploits
None indexed
Exploitation data as of Jul 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Description

Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.

Affected Products

4 products · 7 configurations
OS
windows 11 24h2microsoft
< 10.0.26100.8875
range
OS
windows 11 25h2microsoft
< 10.0.26200.8875
range
OS
windows 11 26h1microsoft
< 10.0.28000.2525
range
OS
windows server 2025microsoft
< 10.0.26100.33158
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every microsoft windows 11 24h2 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 remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Fix

    Apply the microsoft windows 11 24h2 security patch or hotfix for CVE-2026-54990 on the affected version, following the vendor advisory for your exact build.

  3. 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.

  4. How O3 protects you

    O3 detects and blocks CVE-2026-54990 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-2026-54990. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Heap-based buffer overflow in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
O3 Security · Runtime Protection

Is CVE-2026-54990 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-54990 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

CVE-2026-54990: Windows 11 24h2 CWE-122… | O3 Security