CVE-2026-6213: Remote Spark SparkView RCE Vulnerability

CVE-2026-6213 Overview

CVE-2026-6213 is an authentication bypass vulnerability in Remote Spark SparkView builds prior to 1122. The flaw allows an attacker to bypass the local connection check and execute arbitrary code as root on the server. Depending on the deployment, an unauthenticated remote attacker can trigger the issue over the network. The vulnerability is classified under CWE-290: Authentication Bypass by Spoofing. SparkView is an HTML5-based clientless remote desktop and application gateway, so vulnerable instances are often exposed to internal users or directly to the internet.

Critical Impact
Unauthenticated attackers can achieve arbitrary code execution as root on SparkView servers, fully compromising the gateway and any systems it brokers access to.

Affected Products

Remote Spark SparkView builds prior to build 1122
SparkView HTML5 remote desktop and application gateway deployments
Server-side SparkView installations on Linux hosts running as root

Discovery Timeline

2026-05-08 - CVE-2026-6213 published to the National Vulnerability Database
2026-05-08 - Last updated in NVD database

Technical Details for CVE-2026-6213

Vulnerability Analysis

The vulnerability resides in SparkView's local connection check, a control intended to restrict privileged operations to requests originating from the loopback interface. The check can be spoofed or bypassed by a remote attacker, allowing the attacker to invoke privileged code paths that are normally reserved for the local administrator. Because the SparkView server process runs as root, any code reached through the bypassed check executes with full system privileges. The impact extends beyond the gateway itself: SparkView typically holds credentials and session tokens for downstream RDP, SSH, VNC, and Telnet targets, so a compromised gateway can be used to pivot into the wider environment.

Root Cause

The root cause is improper authentication of the request origin, mapped to [CWE-290]. SparkView trusts client-supplied or easily forgeable indicators when deciding whether a connection is "local" rather than relying on the kernel-level socket origin. An attacker who shapes the request appropriately is treated as a trusted local user without presenting valid credentials.

Attack Vector

Exploitation occurs over the network against the SparkView HTTP or WebSocket interface. The attacker submits requests crafted to satisfy the flawed local-connection heuristic, gaining access to administrative or privileged handlers. Those handlers can be abused to load configuration, invoke server-side commands, or otherwise direct the SparkView process to execute attacker-controlled code as root. No user interaction or prior authentication is required in vulnerable configurations. Technical details are referenced in the RemoteSpark release notes.

Detection Methods for CVE-2026-6213

Indicators of Compromise

Unexpected child processes spawned by the SparkView server process, particularly shells (/bin/sh, /bin/bash) or interpreters running as root.
Outbound network connections from the SparkView host to attacker-controlled infrastructure shortly after inbound HTTP or WebSocket traffic.
New or modified files in SparkView installation directories, web roots, or cron/systemd unit paths.
Authentication or session logs showing privileged actions attributed to localhost while the source TCP connection originated from a remote IP.

Detection Strategies

Compare SparkView application logs against network flow records to identify requests recorded as local while sourced from non-loopback peers.
Hunt for SparkView builds older than 1122 across the estate using software inventory data.
Alert on any process descendant of the SparkView Java or service binary that is not part of its normal runtime profile.

Monitoring Recommendations

Forward SparkView access, error, and audit logs to a central SIEM and retain them for at least 90 days.
Monitor the SparkView host for changes to startup scripts, SSH keys, and PAM configuration.
Watch for spikes in failed or unusual requests to SparkView administrative endpoints from the internet.

How to Mitigate CVE-2026-6213

Immediate Actions Required

Upgrade SparkView to build 1122 or later on every server, prioritizing internet-facing instances.
Restrict network access to the SparkView management interface to trusted administrative networks until patching is complete.
Rotate any credentials, private keys, and session secrets stored on or proxied through SparkView servers that ran a vulnerable build.
Review SparkView and downstream target system logs for signs of exploitation before returning hosts to production.

Patch Information

Remote Spark addressed the issue in SparkView build 1122. Administrators should obtain the fixed build from the vendor and verify the running version after upgrade. See the RemoteSpark release notes for the official changelog covering this build.

Workarounds

Place SparkView behind a reverse proxy or VPN that enforces authenticated access before traffic reaches the application.
Block direct external access to SparkView administrative paths at the network edge.
Run SparkView as a dedicated, non-root service account where supported by the deployment, reducing the blast radius of any future bypass.

bash

# Configuration example: restrict SparkView exposure with iptables until patched
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
iptables -A INPUT -p tcp --dport 80 -j DROP