Qwik - RCE (CVE-2026-27971)

CVE-2026-27971 is a critical remote code execution vulnerability in Qwik versions up to 1.19.0, stemming from unsafe deserialization in the server$ RPC mechanism. This flaw allows unauthenticated attackers to execute arbitrary code on affected servers with a single HTTP request, posing a severe risk to any deployment where require() is available at runtime. Exploitation could lead to full system compromise, making immediate patching to version 1.19.1 essential for security.

CrowdSec has been tracking this vulnerability and its exploits since 30th of March 2026.

CrowdSec network observations suggest that most exploitation of CVE-2026-27971 involves focused reconnaissance to identify viable targets. Attackers typically tailor their campaigns based on system exposure and configuration. It is unlikely that a given attack is accidental. CrowdSec network telemetry also shows that exploitation of CVE-2026-27971 has significantly declined over the past week. Attack volumes are well below the long-term average, suggesting attackers are rapidly losing interest. The vulnerability appears to be falling out of active use across most threat landscapes.

Attackers exploit the Qwik server by sending crafted POST requests to the /?qfunc=sync endpoint with malicious JSON payloads, targeting the server$ deserialization mechanism to achieve unauthenticated remote code execution.