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CriticalVulnerabilityCVE-2026-54857updated 29 Oct 2026, 20:04 UTC

Quirky plugin lets attackers run code without logging in

A WordPress-style add-on called Quirky has a flaw that lets anyone on the internet send specially crafted data to the site and make it run commands, without needing a password. Attackers could take over the site or steal its data.

Official, 2 sources
SeverityCriticalCVSS 9.8 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Attacker sends payloadCrafted request to the public website
  2. 2Quirky unpacks dataUntrusted input is deserialized without checks
  3. 3Malicious object runsInjected object triggers code execution
  4. ResultAttacker gains control of the server

What happened

Quirky versions 1.23 and earlier contain an unauthenticated PHP object injection vulnerability, where untrusted input is unsafely deserialized, allowing object injection without authentication.

Why it is dangerous: Successful exploitation can lead to remote code execution, data theft, or full control of the affected site or server, and no login is required to attempt the attack.

Are you affected?

You are affected if you run Quirky version 1.23 or earlier on a PHP-based website.

Quirky <= 1.23

What to do

  1. Check whether Quirky is installed and note its version
  2. Deactivate and remove Quirky if you do not need it
  3. If you must keep it, check the GitHub advisory GHSA-3mrq-9m93-28r2 for a patched release and update immediately
  4. Review the site for unexpected files or admin accounts

Timeline

  1. 29 Oct 2026, 16:18 UTC
    Publicly disclosed
  2. 29 Oct 2026, 16:18 UTC
    Reported by NVD · NVD
  3. 29 Oct 2026, 16:20 UTC
    Picked up by Zero Radar
  4. 29 Oct 2026, 20:04 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-54857 · GHSA-3mrq-9m93-28r2
CVSS
9.8 / 10
EPSS
0.5% chance of exploitation within 30 days
Disclosed
29 Oct 2026, 16:18 UTC
On Zero Radar
29 Oct 2026, 16:20 UTC (2 min after disclosure)
Last change
29 Oct 2026, 20:04 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Quirky plugin lets attackers run code without logging in · Zero Radar