CVE-2025-69653 is a vulnerability identified in the QuickJS JavaScript engine, specifically in the release dated 2025-09-13. The flaw exists in the garbage collection routine, within the function gc_decref_child in quickjs.c. A specially crafted JavaScript input, when executed by the qjs interpreter with the -m option enabled, triggers an internal assertion failure. This assertion failure causes the interpreter to abort execution by raising a SIGABRT signal during garbage collection, resulting in a denial-of-service condition. The root cause is related to improper handling of reference decrements in the garbage collector, which leads to an unexpected state and forced termination of the interpreter process. The vulnerability is classified under CWE-617 (Reachable Assertion) and does not impact confidentiality or integrity, only availability. Exploitation requires the attacker to supply a malicious JavaScript input and have it executed in the vulnerable environment, implying user interaction. The issue was resolved in a commit dated 2025-12-11 (commit 1dbba8a88eaa40d15a8a9b70bb1a0b8fb5b552e6). No public exploits have been reported to date. The CVSS v3.1 base score is 6.5 (medium), reflecting network attack vector, low attack complexity, no privileges required, user interaction needed, and high impact on availability only.

The primary impact of CVE-2025-69653 is denial-of-service, where the QuickJS interpreter crashes unexpectedly during garbage collection when processing malicious JavaScript input. This can disrupt applications or services embedding QuickJS or using it as a scripting engine, potentially causing downtime or degraded service availability. Since QuickJS is often used in embedded systems, IoT devices, and lightweight scripting environments, affected devices may become unresponsive or require manual restart. There is no direct impact on data confidentiality or integrity, but service interruptions could affect business operations, especially in environments relying on automated scripting or real-time processing. The requirement for user interaction and script execution limits remote exploitation but does not eliminate risk in scenarios where untrusted scripts are processed. Organizations embedding QuickJS in products or development tools should consider the risk of DoS attacks that could be triggered by malicious inputs, especially in exposed or multi-tenant environments.

To mitigate CVE-2025-69653, organizations should promptly update QuickJS to the patched version released after 2025-12-11, which includes the fix in commit 1dbba8a88eaa40d15a8a9b70bb1a0b8fb5b552e6. Until patching is possible, restrict or sanitize JavaScript inputs processed by the qjs interpreter, especially when using the -m option. Implement input validation and filtering to detect and block suspicious or malformed scripts that could trigger the assertion failure. Limit the use of the -m option if it is not essential, as the vulnerability is specifically triggered in this mode. Employ runtime monitoring to detect interpreter crashes and automate recovery procedures to minimize downtime. For embedded or IoT devices, ensure secure update mechanisms are in place to deploy patches rapidly. Additionally, isolate QuickJS execution environments to contain potential DoS impacts and prevent cascading failures in dependent systems.