CVE-2025-14136 Overview
CVE-2025-14136 is a stack-based buffer overflow affecting multiple Linksys range extender models, including the RE6500, RE6250, RE6300, RE6350, RE7000, and RE9000. The flaw resides in the RE2000v2Repeater_get_wired_clientlist_setClientsName function within mod_form.so. Attackers manipulate the clientsname_0 argument to overflow a stack buffer, enabling remote exploitation. According to the disclosure, the exploit has been publicly released and the vendor did not respond to early disclosure attempts. The vulnerability maps to [CWE-119] and [CWE-787] and impacts confidentiality, integrity, and availability of affected devices.
Critical Impact
Remote attackers with low privileges can trigger a stack-based buffer overflow on internet-facing range extenders, potentially achieving arbitrary code execution and full device compromise.
Affected Products
- Linksys RE6500 firmware 1.0.013.001, RE6250 / RE6350 firmware 1.0.04.001
- Linksys RE6300 firmware 1.2.07.001, RE7000 firmware 1.1.05.003
- Linksys RE9000 firmware 1.0.04.002
Discovery Timeline
- 2025-12-06 - CVE-2025-14136 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-14136
Vulnerability Analysis
The vulnerability is a stack-based buffer overflow [CWE-121, CWE-787] in the RE2000v2Repeater_get_wired_clientlist_setClientsName function inside the shared library mod_form.so. This function processes wired client list updates and accepts a clientsname_0 argument supplied through the device's web management interface. The function copies the attacker-controlled string into a fixed-size stack buffer without enforcing length validation. When the supplied value exceeds the buffer size, adjacent stack memory is overwritten, including saved return addresses and frame pointers. EPSS data indicates a probability of 0.963% for near-term exploitation activity.
Root Cause
The root cause is the absence of bounds checking on the clientsname_0 parameter before it is written to a stack-allocated buffer. The vulnerable code path likely uses an unsafe string copy primitive such as strcpy or sprintf without length constraints. Because the function is reachable from the HTTP management interface, the input boundary check should occur before the data enters native code parsing.
Attack Vector
The attack is launched over the network against the device's management interface. The CVSS vector requires low privileges (PR:L), meaning the attacker must hold valid credentials or hijack an authenticated session to reach the vulnerable handler. A crafted HTTP request containing an oversized clientsname_0 value drives execution into the vulnerable function. Successful exploitation overwrites the return address on the stack, redirecting control flow. On MIPS or ARM-based extenders without ASLR or stack canaries, this typically yields arbitrary code execution as the web server process.
The vulnerable code path resides in mod_form.so and is reached through the wired client list configuration endpoint. Technical details and a proof-of-concept are documented in the public GitHub vulnerability writeup and tracked as VulDB #334525.
Detection Methods for CVE-2025-14136
Indicators of Compromise
- Unusually long clientsname_0 parameter values in HTTP POST requests to the range extender administrative interface.
- Unexpected reboots, web service crashes, or httpd restarts on affected Linksys RE-series devices.
- Outbound connections from the extender to unknown hosts, indicating possible post-exploitation command-and-control.
Detection Strategies
- Inspect HTTP traffic destined for Linksys extender management endpoints and alert on parameter values exceeding expected length thresholds.
- Monitor device syslog output for segmentation faults or process restarts in mod_form.so-linked services.
- Apply network IDS signatures that match oversized form fields targeting RE2000v2Repeater_get_wired_clientlist_setClientsName.
Monitoring Recommendations
- Place Linksys range extenders on isolated management VLANs and log all administrative session activity.
- Forward device logs to a centralized SIEM for anomaly correlation across firmware versions listed in the advisory.
- Track authentication events to the extender web interface for brute-force or credential reuse patterns that could precede exploitation.
How to Mitigate CVE-2025-14136
Immediate Actions Required
- Disable remote administration on all affected Linksys RE6500, RE6250, RE6300, RE6350, RE7000, and RE9000 devices.
- Restrict access to the web management interface to a trusted management subnet only.
- Rotate administrative credentials and enforce strong, unique passwords on every extender.
Patch Information
No vendor patch is currently available. The advisory notes that Linksys was contacted before public disclosure but did not respond. Organizations operating these end-of-support range extenders should treat the devices as unpatched and plan replacement with a supported model. Monitor the Linksys support site for any future firmware updates addressing CVE-2025-14136.
Workarounds
- Segment range extenders away from sensitive internal networks using firewall rules that block inbound HTTP/HTTPS to the device.
- Disable the wired client list feature where configurable, removing the attack surface exposed by mod_form.so.
- Replace affected end-of-life Linksys RE-series extenders with currently supported hardware that receives security updates.
# Example: block external access to extender management interface
iptables -A FORWARD -d <extender_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <extender_ip> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
