CVE-2026-57276 Overview
CVE-2026-57276 is a stack buffer overflow vulnerability in GeoVision's GeoWebPlayer addon, also known as Web Plugin in GV-VMS documentation and WS Player for VMS-Cloud. The addon runs a local WebSocket server that expands the capabilities of GeoVision web interfaces. The connectionInfo command handler copies attacker-controlled JSON strings into fixed-size buffers using manual byte-by-byte loops without length checks. An attacker who tricks a user into visiting a malicious page can trigger memory corruption in the handle_connect_info function through the password field. The flaw is classified as [CWE-120] Buffer Copy without Checking Size of Input.
Critical Impact
Successful exploitation can lead to arbitrary code execution in the context of the GeoWebPlayer process running on the victim host.
Affected Products
- GeoVision GeoWebPlayer (Web Plugin)
- GeoVision GV-VMS with GeoWebPlayer addon installed
- GeoVision GV-Cloud / VMS-Cloud with WS Player addon installed
Discovery Timeline
- 2026-07-02 - CVE-2026-57276 published to NVD
- 2026-07-02 - Last updated in NVD database
Technical Details for CVE-2026-57276
Vulnerability Analysis
GeoWebPlayer creates a WebSocket server listening on localhost that accepts commands from browser contexts on the same machine. Among the supported commands, connectionInfo provides parameters required to connect the plugin to a camera stream. The handler internally referenced as handle_connect_info parses a JSON payload and copies several string fields into fixed-size stack buffers.
The copy routines are implemented as manual byte-by-byte loops that terminate only on a null byte or JSON delimiter. They do not enforce the destination buffer size. When a caller supplies an oversized password value with the key present, the loop writes past the end of the destination buffer and corrupts adjacent stack memory, including saved return addresses.
Exploitation requires user interaction because the malicious WebSocket message must originate from a page loaded by the user. The attack complexity is high due to the need to bypass typical browser and process mitigations, but a successful chain yields high impact to confidentiality, integrity, and availability with scope change beyond the vulnerable component.
Root Cause
The root cause is missing bounds validation in string handling inside handle_connect_info. The developer copied JSON-derived values using a custom loop rather than a length-checked function such as strncpy_s or snprintf. Any JSON string field consumed by this handler that lacks a size check is a candidate for overflow, and the password field is one confirmed instance.
Attack Vector
An attacker hosts a web page that opens a WebSocket connection to the GeoWebPlayer localhost port and sends a crafted connectionInfo JSON message containing an oversized password value. When a victim with GeoWebPlayer installed visits the page, the browser initiates the WebSocket handshake and the plugin parses the attacker-controlled JSON. The overflow corrupts stack memory in the plugin process, enabling control-flow hijack.
The vulnerability manifests in the handle_connect_info command dispatch path. See the Talos Intelligence Vulnerability Report for the disassembly and proof-of-concept payload structure.
Detection Methods for CVE-2026-57276
Indicators of Compromise
- Unexpected crashes or restarts of the GeoWebPlayer or WS Player process on endpoints with GeoVision software installed.
- Outbound WebSocket connections from browser processes to GeoWebPlayer's localhost listening port originating from untrusted web origins.
- Presence of oversized password or other string fields in connectionInfo JSON messages captured on the loopback interface.
Detection Strategies
- Monitor process integrity of GeoWebPlayer binaries and alert on abnormal child processes spawned by the plugin.
- Inspect loopback traffic on the GeoWebPlayer WebSocket port for connectionInfo messages with abnormally long field values.
- Correlate browser-initiated WebSocket connections to localhost with subsequent process anomalies on the same host.
Monitoring Recommendations
- Enable crash and Windows Error Reporting telemetry collection for the GeoWebPlayer process and forward events to your SIEM.
- Track installation inventory for GeoVision GV-VMS, GV-Cloud, and the GeoWebPlayer/WS Player addon across managed endpoints.
- Review the GeoVision Cyber Security advisories for updated fixed version details and hash information.
How to Mitigate CVE-2026-57276
Immediate Actions Required
- Inventory all endpoints with GeoVision GV-VMS, GV-Cloud, or the GeoWebPlayer / WS Player addon installed.
- Restrict use of GeoVision web interfaces to trusted browsers and workstations, and instruct users not to browse arbitrary sites while GeoWebPlayer is running.
- Apply the vendor patch as soon as GeoVision publishes a fixed release for the affected addon.
Patch Information
GeoVision publishes security updates and version guidance on the GeoVision Cyber Security page. Refer to TALOS-2026-2375 for the specific vulnerable build identifiers and coordinated fix status.
Workarounds
- Uninstall the GeoWebPlayer / WS Player addon on hosts that do not require the WebSocket-backed web interface features.
- Block the GeoWebPlayer WebSocket listener at the local firewall so only explicitly approved browser sessions can reach it.
- Enforce host-based browser policies that prevent navigation to untrusted origins on workstations running GeoVision management software.
# Windows: identify GeoWebPlayer processes and its listening ports
tasklist /FI "IMAGENAME eq GeoWebPlayer.exe"
netstat -ano | findstr /I "LISTENING" | findstr 127.0.0.1
# Block the GeoWebPlayer WebSocket port at the local firewall (example port)
netsh advfirewall firewall add rule name="Block GeoWebPlayer WS" ^
dir=in action=block protocol=TCP localport=<GeoWebPlayer_port>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
