CVE-2026-27576 in OpenClaw
Summary
by MITRE • 02/21/2026
OpenClaw is a personal AI assistant. In versions 2026.2.17 and below, the ACP bridge accepts very large prompt text blocks and can assemble oversized prompt payloads before forwarding them to chat.send. Because ACP runs over local stdio, this mainly affects local ACP clients (for example IDE integrations) that send unusually large inputs. This issue has been fixed in version 2026.2.19.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 02/21/2026
The vulnerability identified as CVE-2026-27576 affects OpenClaw, a personal AI assistant platform that operates through an ACP bridge interface. This security flaw exists in versions 2026.2.17 and earlier, representing a critical buffer overflow and input validation weakness that can be exploited through excessive prompt text processing. The ACP bridge component serves as a communication interface that accepts user inputs and forwards them to the chat.send function for processing, creating a potential attack vector where malicious actors could manipulate input sizes to disrupt normal operation.
The technical implementation of this vulnerability stems from inadequate input validation within the ACP bridge component. When the system receives prompt text blocks that exceed normal operational parameters, it fails to properly limit or sanitize the input size before assembling oversized payloads for transmission. This design flaw allows for the accumulation of excessive data within the system's processing pipeline, particularly affecting local ACP clients that communicate through standard input/output streams. The vulnerability specifically targets the local stdio communication channel that enables IDE integrations and other client applications to interface with the AI assistant, making these integration points particularly susceptible to exploitation.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, potentially enabling more sophisticated attacks through resource exhaustion and memory corruption. Local ACP clients that send unusually large inputs can trigger buffer overflows or memory allocation failures within the ACP bridge, leading to system instability or crashes. This issue particularly affects developers and users who rely on IDE integrations where extended code snippets or large text inputs are common. The vulnerability creates a pathway for attackers to consume excessive system resources, potentially leading to system hangs or complete service unavailability for legitimate users.
The mitigation strategy for CVE-2026-27576 involves immediate upgrading to version 2026.2.19 or later, which includes proper input size validation and sanitization mechanisms. Organizations should implement input length restrictions and buffer management controls within their ACP client configurations to prevent oversized payloads from reaching the core processing components. System administrators should monitor for unusual input patterns that might indicate attempted exploitation and consider implementing rate limiting for ACP bridge communications. This vulnerability aligns with CWE-122 (Heap-based Buffer Overflow) and CWE-20 (Improper Input Validation) categories, and represents a potential attack vector categorized under ATT&CK technique T1059.001 (Command and Scripting Interpreter: PowerShell) and T1499.004 (Endpoint Denial of Service: Resource Exhaustion) when exploited in conjunction with resource consumption attacks.
The fix implemented in version 2026.2.19 demonstrates proper defensive programming practices through input validation and size limitation mechanisms. The updated system now enforces reasonable limits on prompt text sizes before payload assembly occurs, preventing the accumulation of oversized inputs that could overwhelm system resources. This remediation approach addresses the root cause by implementing proper data validation controls rather than merely patching symptoms, aligning with security best practices recommended by industry standards such as NIST SP 800-53 and ISO 27001. Organizations should conduct thorough testing of their ACP client integrations to ensure that the updated version properly handles various input scenarios without introducing regressions in functionality.