WordPress Update Fix Can Still Leave Sites Vulnerable During Install
A recently patched WordPress flaw can still be exploited while applying the update. Security researchers warn of server-level risks during installation.
TL;DR
- A patched WordPress vulnerability can still be exploited mid-update.
- The installer uses outdated code, creating a window for remote code execution.
- Researchers advise blocking web access during the update process.
- Site admins should act immediately to reduce exposure risk.
- Organizations using WordPress should monitor for suspicious activity.
A critical vulnerability in WordPress continues to pose a risk even after administrators apply the official patch. According to Umut Bayram, a researcher at Picus Security who discovered the flaw, the update process itself introduces a brief but dangerous window for exploitation.
While the patch resolves the issue in the updated version, the installation mechanism temporarily relies on the older, unpatched code. This allows attackers who time their actions correctly to execute arbitrary code on the server, potentially gaining full control over the affected website.
How the Vulnerability Works
- The flaw lies in how WordPress unpacks update files during installation.
- Older, vulnerable code is executed before the new files take effect.
- Attackers can inject malicious payloads if they strike during this phase.
- Successful exploitation grants server-level access to the attacker.
Mitigation Recommendations
- Block all web access to the site during the update process.
- Use maintenance mode plugins or server-level configurations to prevent requests.
- Monitor logs closely for unusual activity around update times.
- Ensure updates are performed during low-traffic periods to minimize impact.
- Consider manual patch deployment in high-security environments.
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