CSSA Exclusive Early Warning9.8 Critical
fastjson2 autoType allowlist validation flaw leading to remote code execution
The vulnerability arises because, when SupportAutoType is not enabled under the default configuration, the AutoType-disabled validation branch in fastjson2 performs prefix matching using only FNV-1a incremental hashes against default accept hashes, and does not re-verify whether the input text actually equals an allowlisted class name after a match. An attacker can construct an FNV chosen-prefix hash collision for any prefix and inject URL-form type names such as jar:/file:/http: into the @type field of the JSON request body, causing the string to be loaded and resolved by the application's context class loader and ultimately triggering arbitrary remote code execution on the server. Exploitation requires no authentication, no user interaction and no known dangerous class on the target system — only attacker control of the JSON request body.
Component
fastjson2 is a high-performance Java JSON serialization and deserialization library open-sourced by Alibaba. Its architecture uses streaming parsing a…
Type
Deserialization of Untrusted Data (CWE-502)
Repo
Remediation- Refer to the PR #7695 patch, which adds acceptNameSet allowlist text re-verification in ContextAutoTypeBeforeHandler and ObjectReaderProvider and rejects type names containing ':' or '!' outright, thereby eliminating the FNV chosen-prefix hash collision bypass. As a temporary mitigation, enable SafeMode (JVM parameter -Dfastjson2.parser.safeMode=true) or switch to the noneautotype build to disable AutoType entirely, and intercept JSON request bodies containing an @type key at the WAF layer. It is also recommended to enforce a strict type allowlist on deserialization input, remove unnecessary class loading paths, and use security monitoring (RASP, DAST) for continuous detection of suspicious @type payloads.
CSSA Exclusive Early Warning10.0 Critical
zeroclaw brute-forced due to missing rate-limit validation leading to node compromise
This flaw stems from the gateway pairing module failing to properly integrate standardized client identifier resolution, instead trusting forgeable proxy forwarding header fields as the basis for rate counting, which renders the request throttling mechanism entirely ineffective. An attacker can issue an enormous volume of blind guesses against the six-digit pairing code by supplying continuously varying source address identifiers, breaking through the preset attempt threshold and completing a brute-force attack over the public network with no interaction required. Once a valid credential is obtained, the attack chain converts it into a legitimate session token and takes over the instruction scheduling privileges of the affected node, resulting in disclosure of core system configuration and unauthorized operations.
Component
zeroclaw is an open-source automation control framework for distributed edge computing and IoT gateway scenarios. Its core architecture uses a modular…
Type
Improper Restriction of Excessive Authentication Attempts (CWE-307)
Repo
Remediation- It is recommended to enforce rate counting based on the underlying transport layer address at authentication endpoints and to deploy a global sliding-window rate limiter. An exponential backoff penalty mechanism should be implemented, combined with temporary credential expiration policies and anomalous behavior detection, to fundamentally close off high-frequency brute-force paths.
