OpenClaw before 2026.4.8 improperly validates input in base64 decode paths, allocating memory before enforcing decoded‑size limits. Because of this oversight, an attacker can supply crafted base64 strings that trigger excessive memory allocation, exhausting system resources and causing the service to crash. This flaw is a classic example of CWE-770, where resources are allocated without adequate limits, and it results only in denial of service, not remote code execution.

The product affected is OpenClaw:OpenClaw. All releases prior to 2026.4.8 are vulnerable, including any intermediate patch levels that do not include the fix.

The CVSS score of 5.3 classifies the vulnerability as moderate severity. No EPSS score is available, making it difficult to gauge exploitation probability; however, because the flaw relies on an input decoding function that is commonly exposed, a remote attacker could likely trigger it by sending large base64 payloads to the affected API endpoints. The vulnerability is not listed in the CISA KEV catalog, suggesting no widespread exploitation has been documented. The attack is inferred to be remote, based on the exposure of base64 decode functions in network services.