CVE-2026-11735 Overview
CVE-2026-11735 is a stack-based buffer overflow [CWE-121] affecting multiple NETGEAR router models. An authenticated administrator on an adjacent network can trigger the overflow to make unauthorized modifications to the router's software and functionality. NETGEAR disclosed the issue in its NETGEAR August 2026 Security Advisory.
The flaw requires high privileges (administrator credentials) and adjacent network access, which limits the practical attack surface. Exploitation targets integrity of the router firmware rather than confidentiality or availability of network traffic passing through the device.
Critical Impact
An authenticated admin with adjacent network access can corrupt router memory to alter device software and functionality on affected NETGEAR consumer and gaming routers.
Affected Products
- NETGEAR R7000, RAX20, RAX35v2, RAX41, RAX41v2, RAX42, RAX42v2, RAX43, RAX43v2
- NETGEAR RAX45, RAX49s, RAX50, RAX50s, RAX50v2, RAX54sv2, RAXE450, RAXE500
- NETGEAR XR1000 and XR1000v2 gaming routers
Discovery Timeline
- 2026-08-11 - CVE-2026-11735 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-11735
Vulnerability Analysis
The vulnerability is a stack-based buffer overflow classified under [CWE-121]. It resides in the administrative interface of the affected NETGEAR routers. An authenticated administrator submits input that exceeds a fixed-size stack buffer, corrupting adjacent stack memory including saved return addresses and local variables.
The attack vector is adjacent network, meaning the attacker must reach the router's management interface from the local network segment. Remote exploitation across the internet is not indicated in the advisory. The impact is limited to integrity: the attacker can modify router software and behavior but does not directly gain confidentiality or availability impact per the CVSS vector.
NETGEAR has not published detailed technical analysis of the vulnerable component. Refer to the NETGEAR August 2026 Security Advisory for firmware-specific details.
Root Cause
The root cause is missing or insufficient bounds checking on input handled by a routine in the router firmware. When the routine copies attacker-supplied data into a fixed-size stack buffer, it writes past the buffer boundary. The write corrupts control data on the stack, enabling modification of software behavior.
Attack Vector
An attacker with valid administrator credentials must connect to the router from the same network segment. Once authenticated, the attacker sends a crafted request to the vulnerable endpoint containing an oversized payload. Successful exploitation modifies router firmware behavior. Because administrator credentials are required, credential theft, default password use, or insider access are the practical prerequisites.
No public proof-of-concept exploit is currently available for CVE-2026-11735.
Detection Methods for CVE-2026-11735
Indicators of Compromise
- Unexpected changes to router configuration, firmware version strings, or administrative accounts on the affected NETGEAR models
- Administrator logins from unusual internal hosts followed by abnormally large HTTP POST bodies to management endpoints
- Router reboots, crashes, or service restarts immediately following administrative sessions
Detection Strategies
- Monitor router administrative interfaces for oversized parameter values in HTTP requests to /cgi-bin/ and configuration endpoints
- Compare running firmware hashes and configuration snapshots against known-good baselines on a scheduled basis
- Alert on administrative logins originating from hosts that do not normally manage network infrastructure
Monitoring Recommendations
- Forward router syslog, authentication, and crash logs to a centralized log platform for correlation and long-term retention
- Track administrative session activity and configuration changes on all NETGEAR devices identified in the advisory
- Enable and review DHCP, ARP, and switch port logs to identify unauthorized adjacent-network devices attempting to reach router management interfaces
How to Mitigate CVE-2026-11735
Immediate Actions Required
- Apply the firmware updates listed in the NETGEAR August 2026 Security Advisory for each affected model
- Rotate router administrator passwords and ensure they are unique and strong on all affected devices
- Restrict administrative interface access to trusted management hosts and VLANs only
Patch Information
NETGEAR has released firmware updates addressing CVE-2026-11735 for the affected R7000, RAX-series, RAXE-series, and XR1000-series routers. Download the latest firmware from the corresponding product support page, such as the NETGEAR R7000 Support Page or the NETGEAR XR1000 Support Page. Verify firmware version after installation.
Workarounds
- Disable remote management on the WAN interface if it is not required
- Segment the router management network away from user workstations and guest Wi-Fi to reduce adjacent-network exposure
- Limit the number of accounts with administrator privileges and audit them regularly
# Example: verify installed firmware version after patch (NETGEAR CLI over SSH where supported)
show version
show running-config | include admin
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
