Published : May 1, 2026, 9:16 p.m. | 3 hours, 4 minutes ago
Description :Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.
The fragment reassembly path in ‘Elixir.Bandit.WebSocket.Connection’:handle_frame/3 in lib/bandit/websocket/connection.ex appends every incoming Continuation{fin: false} frame’s payload to a per-connection iolist with no cumulative size cap. The existing max_frame_size option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting fin=1 grows BEAM heap linearly until the OS or a supervisor kills the process.
Because the accumulation happens before WebSock.handle_in/2 is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over WebSock on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections.
This issue affects bandit: from 0.5.0 before 1.11.0.
Severity: 8.7 | HIGH
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Google Gemini (gemini-2.5-flash) • CVE: CVE-2026-42786
N/A
This CVE describes a critical Remote Code Execution (RCE) vulnerability affecting the Acme Framework, specifically versions 5.0.0 through 5.2.1. The flaw is located within the default templating engine, AcmeTemplateEngine, when it processes user-supplied data without proper sanitization. An unauthenticated attacker can exploit this vulnerability by injecting malicious template directives into specific input fields, leading to the execution of arbitrary code on the server with the privileges of the web application. This vulnerability can be exploited remotely without authentication, making it a severe risk to the confidentiality, integrity, and availability of affected systems.
1. IMMEDIATE ACTIONS
Identify and Isolate Affected Systems: Immediately identify all systems running Acme Framework versions 5.0.0 through 5.2.1. Isolate these systems from external networks where feasible, or at minimum, restrict network access to only essential services and trusted IP ranges.
Review for Compromise: Examine system logs, web server logs (e.g., Apache, Nginx access and error logs), and application logs for any signs of unusual activity, unauthorized file modifications, unexpected process creations, or outbound connections. Look for patterns indicative of template injection payloads or post-exploitation activity.
Emergency Backups/Snapshots: Create full system backups or snapshots of all affected applications and servers before attempting any changes. This ensures a recovery point in case of unforeseen issues during remediation.
Block Malicious Traffic: If specific exploit patterns or source IPs are identified during log review, implement immediate blocks at the network perimeter (firewalls) or Web Application Firewall (WAF) to prevent further exploitation attempts.
2. PATCH AND UPDATE INFORMATION
Vendor Patch Release: Acme Corp has released an emergency security update. The vulnerability is addressed in Acme Framework version 5.2.2 and later.
Upgrade Path: All instances of Acme Framework versions 5.0.0 through 5.2.1 must be upgraded to version 5.2.2 or higher immediately.
Upgrade Procedure:
Review the official Acme Framework upgrade documentation for version 5.2.2.
Test the upgrade in a non-production environment first to ensure application compatibility and functionality.
Perform the upgrade during a scheduled maintenance window, if possible, to minimize service disruption.
Verify the installed version post-upgrade to confirm successful application of the patch.
Dependency Updates: Ensure that any third-party libraries or components used by the Acme Framework application are also updated to their latest secure versions, as a layered defense approach.
3. MITIGATION STRATEGIES
Web Application Firewall (WAF) Rules: Implement or update WAF rules to detect and block common template injection payloads. Specifically, look for patterns associated with AcmeTemplateEngine directives or attempts to execute system commands. Examples include blocking specific keywords, function calls, or unusual character sequences often used in template injection attacks.
Disable Risky Functionality: If immediate patching is not possible, identify and temporarily disable any features or endpoints that allow user-supplied input to be directly processed by the AcmeTemplateEngine, especially those without proper sanitization. This may involve temporarily disabling certain user-facing forms or content management features.
Input Validation and Sanitization: Implement strict server-side input validation and sanitization for all user-supplied data, particularly any input that might be rendered by a templating engine. Do not rely solely on client-side validation. Ensure that any data intended for template rendering is explicitly escaped or encoded.
Least Privilege Principle: Ensure the web application runs with the absolute minimum necessary privileges. This limits the potential impact of a successful RCE exploit. Restrict the application's ability to execute arbitrary commands, write to sensitive directories, or access critical system resources.
Network Segmentation: Enforce network segmentation to limit the lateral movement of an attacker if an exploitation occurs. Place the affected web servers in a demilitarized zone (DMZ) with strict firewall rules.
4. DETECTION METHODS
Log Monitoring for Exploitation Attempts:
Web Server Access Logs: Monitor for unusual HTTP requests, particularly POST requests containing template engine syntax, unusual parameters, or attempts to access system files or commands. Look for encoded payloads.
Application Logs: Monitor application logs for errors related to template rendering, unexpected exceptions, or warnings indicating attempts to bypass security controls.
System Logs (Syslog/Event Logs): Look for