CVE-2023-36109

What it actually does

Buffer overflow in ecma_stringbuilder_append_raw allows remote attackers to overwrite memory and execute arbitrary code.

Why it matters to the business

Compromise of systems using the affected JavaScript engine can lead to full remote takeover, data theft, or use as an entry point for further attacks; the vulnerability remains exploitable years after disclosure with a publicly available exploit.

How an attack unfolds

An attacker sends a specially crafted input that reaches the ecma_stringbuilder_append_raw function, triggering an out-of-bounds write that corrupts memory and redirects execution to attacker-controlled code; the flaw is reachable over the network without authentication.

How to fix it

Upgrade JerryScript to the latest available version that contains a fix for the buffer overflow; if no upstream release exists, apply a backported patch that bounds the copy operation in ecma-helpers-string.c or replace the engine with a maintained alternative.

How to confirm the fix worked

Confirm the ecma_stringbuilder_append_raw function contains length checks before the memcpy operation; recompile and test with the original proof-of-concept input to verify the crash or code execution no longer occurs.

Typical attack path

1. Locate a network-exposed or locally reachable application embedding the vulnerable JerryScript engine
2. Craft input that passes through string-building operations to reach ecma_stringbuilder_append_raw
3. Trigger the buffer overflow to corrupt control structures in memory
4. Redirect execution to injected or ROP-based payload for code execution

How to detect it

Review application or system logs for unexpected crashes or memory corruption signals near string handling routines; inspect inbound network traffic or API calls that feed raw strings into the engine for unusually large or malformed payloads.

What your security team should do

• Prioritize inventory of all embedded JerryScript deployments and schedule upgrades
• Apply network segmentation and input sanitization around any unpatched instances
• Monitor EPSS trend and exploit availability for increased urgency if scores rise