CVE-2026-103569 Overview
CVE-2026-103569 is an out-of-bounds read vulnerability [CWE-125] in the Windows Internet Key Exchange (IKE) Extension. An unauthorized remote attacker can send crafted network traffic to the IKE service and read memory outside the intended buffer bounds. Successful exploitation discloses sensitive information from the targeted system over the network.
The flaw requires no authentication, no user interaction, and has low attack complexity. Microsoft published the advisory on October 13, 2026, and the issue affects the Windows IKE Extension component used for IPsec key negotiation.
Critical Impact
Remote, unauthenticated attackers can read process memory from the Windows IKE Extension across the network, exposing sensitive data without triggering authentication or user prompts.
Affected Products
- Microsoft Windows (IKE Extension component)
- Systems running IPsec with the Windows IKE service exposed
- See the Microsoft CVE-2026-103569 Update Guide for the full list of affected builds
Discovery Timeline
- 2026-10-13 - CVE-2026-103569 published to NVD
- 2026-10-13 - Last updated in NVD database
Technical Details for CVE-2026-103569
Vulnerability Analysis
The vulnerability resides in the Windows IKE Extension, which handles Internet Key Exchange protocol messages used to establish IPsec security associations. The service processes attacker-controlled packet fields without properly validating length or offset values before reading from memory.
An attacker reaches the vulnerable code path by sending a malformed IKE message to UDP port 500 or 4500 on a target that exposes the IKE service. The out-of-bounds read returns adjacent process memory, which may contain cryptographic material, session state, or other sensitive data. The impact is limited to confidentiality; integrity and availability of the target are not directly affected.
EPSS currently estimates a 1.005% exploitation probability (62nd percentile), reflecting that no public proof-of-concept has been observed.
Root Cause
The root cause is missing or insufficient bounds checking in the IKE message parser [CWE-125]. The parser trusts length or index fields supplied by the remote peer and reads beyond the allocated buffer when those values are crafted to exceed the actual packet or buffer size.
Attack Vector
The attack vector is network-based. An attacker sends a specially crafted IKE packet to a Windows host accepting IKE traffic. No credentials, prior access, or user interaction are required. Because IKE listens on UDP, source addresses can be spoofed in some scenarios, complicating attribution.
No public exploit code or proof-of-concept has been published. Refer to the Microsoft CVE-2026-103569 Update Guide for vendor-supplied technical details.
Detection Methods for CVE-2026-103569
Indicators of Compromise
- Unexpected IKE/ISAKMP traffic to UDP ports 500 and 4500 from untrusted sources
- Malformed or oversized IKE packets flagged by network intrusion detection sensors
- Repeated IKE negotiation failures or anomalous IKEEXT service events in the Windows event log
Detection Strategies
- Deploy IDS/IPS signatures that validate IKE message length and payload field consistency against RFC 7296
- Inspect Windows event logs for IKEEXT warnings, parsing errors, or service crashes correlated with inbound UDP 500/4500 traffic
- Baseline normal IPsec peers and alert on IKE sessions initiated from unexpected sources
Monitoring Recommendations
- Capture full packet data for inbound IKE traffic on internet-facing hosts for forensic review
- Monitor volume and source diversity of IKE requests to detect scanning or probing campaigns
- Correlate IKE anomalies with host-based telemetry to identify memory disclosure attempts targeting the IKEEXT service
How to Mitigate CVE-2026-103569
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft CVE-2026-103569 Update Guide as soon as testing permits
- Inventory Windows systems exposing UDP 500 and 4500 to untrusted networks and prioritize those for patching
- Restrict IKE traffic at perimeter firewalls to known IPsec peer addresses
Patch Information
Microsoft released a security update for CVE-2026-103569 on October 13, 2026. Consult the Microsoft CVE-2026-103569 Update Guide for KB article numbers, affected builds, and update availability per Windows version.
Workarounds
- Block inbound UDP 500 and 4500 at network perimeters where IPsec is not required
- Disable the IKEEXT service on hosts that do not use IPsec, after validating no dependencies exist
- Enforce IPsec peer allowlists on host firewalls to limit which sources can initiate IKE negotiation
# Example: block inbound IKE traffic from untrusted networks using Windows Firewall
New-NetFirewallRule -DisplayName "Block Untrusted IKE UDP 500" -Direction Inbound -Protocol UDP -LocalPort 500 -RemoteAddress Any -Action Block
New-NetFirewallRule -DisplayName "Block Untrusted IKE UDP 4500" -Direction Inbound -Protocol UDP -LocalPort 4500 -RemoteAddress Any -Action Block
# Optional: disable the IKE and AuthIP Keying Modules service on hosts that do not use IPsec
Set-Service -Name IKEEXT -StartupType Disabled
Stop-Service -Name IKEEXT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.