CVE-2026-24892: openITCOCKPIT PHP Deserialization Vulnerability

CVE-2026-24892 Overview

openITCOCKPIT is an open source monitoring tool built for different monitoring engines like Nagios, Naemon and Prometheus. A significant insecure deserialization vulnerability has been identified in openITCOCKPIT Community Edition version 5.3.1 and earlier. The vulnerability exists in the processing of changelog entries where serialized changelog data derived from attacker-influenced application state is unserialized without restricting allowed classes.

Although no current application endpoint was found to introduce PHP objects into this data path, the presence of an unrestricted unserialize() call constitutes a latent PHP object injection vulnerability. If future code changes, plugins, or refactors introduce object values into this path, the vulnerability could become immediately exploitable with severe impact, including potential remote code execution.

Critical Impact

This latent insecure deserialization vulnerability in openITCOCKPIT could enable remote code execution if future code changes introduce exploitable object injection paths. Organizations should upgrade to version 5.4.0 immediately to eliminate this risk.

Affected Products

• openITCOCKPIT Community Edition version 5.3.1 and earlier
• openITCOCKPIT installations utilizing changelog processing functionality
• Systems running vulnerable versions with Nagios, Naemon, or Prometheus monitoring engines

Discovery Timeline

• 2026-02-20 - CVE-2026-24892 published to NVD
• 2026-02-23 - Last updated in NVD database

Technical Details for CVE-2026-24892

Vulnerability Analysis

This vulnerability falls under CWE-502 (Deserialization of Untrusted Data), a well-documented weakness class that can lead to severe security impacts. The vulnerability exists in two key components of the openITCOCKPIT codebase: the Gearman Worker Command handler (GearmanWorkerCommand.php) and the Changelogs Controller (ChangelogsController.php).

The core issue is the use of PHP's unserialize() function without restricting the classes that can be instantiated during deserialization. PHP object injection vulnerabilities occur when user-controllable data is passed to unserialize() without proper class restrictions, potentially allowing attackers to instantiate arbitrary objects and trigger dangerous magic methods like __wakeup(), __destruct(), or __toString().

While the current codebase does not expose a direct exploitation path, the latent nature of this vulnerability means that any future code change, plugin installation, or refactoring that introduces attacker-controllable serialized objects into these code paths would immediately create an exploitable condition.

Root Cause

The root cause of this vulnerability is the unsafe usage of PHP's unserialize() function without the allowed_classes option. When processing changelog data and Gearman worker payloads, the application deserializes data without restricting which PHP classes can be instantiated. This design flaw creates a latent object injection vulnerability that could be triggered by future code modifications or plugin installations that introduce attacker-controlled serialized data.

Attack Vector

The attack vector for this vulnerability is network-based, requiring low privileges but high attack complexity. An attacker would need to find or create a code path that introduces malicious serialized PHP objects into the changelog processing or Gearman worker payload handling. If such a path exists or is introduced:

1. The attacker crafts a malicious serialized PHP object containing a gadget chain
2. The malicious payload is introduced into the application's data flow
3. When unserialize() is called without class restrictions, the attacker's objects are instantiated
4. Magic methods on the instantiated objects execute, potentially leading to remote code execution

The following patches from the GitHub security commit show the vulnerable and fixed code:

Patch in src/Command/GearmanWorkerCommand.php:

         } catch (\Exception $e) {
             $payloadFromJSON = '';
         }
-        $payload = @unserialize($payload);
+        $payload = @unserialize($payload, ['allowed_classes' => false]);

         if (!is_array($payload)) {
             if (!is_array($payloadFromJSON)) {

Source: GitHub Commit 975e0d0

Patch in src/Controller/ChangelogsController.php:

                 $all_changes[$index]['time'] = $UserTime->customFormat('H:i:s', $changeTimestamp);
             }

-            $dataUnserialized = unserialize($change['data']);
+            $dataUnserialized = unserialize($change['data'], ['allowed_classes' => false]);
             $dataUnserialized = $ChangelogsTable->replaceFieldValues($dataUnserialized);
             $dataUnserialized = $ChangelogsTable->formatDataForView($dataUnserialized);
             $dataUnserialized = $ChangelogsTable->replaceTableNames($dataUnserialized);

Source: GitHub Commit 975e0d0

The fix adds ['allowed_classes' => false] as the second parameter to unserialize(), which prevents any PHP objects from being instantiated during deserialization, converting them to __PHP_Incomplete_Class objects instead.

Detection Methods for CVE-2026-24892

Indicators of Compromise

• Unusual serialized PHP object patterns in changelog database entries containing unexpected class names
• Anomalous Gearman worker payloads with serialized object structures beyond expected array data
• Web application logs showing PHP errors related to object instantiation during changelog processing
• Unexpected file system changes or process spawning following changelog viewing operations

Detection Strategies

• Implement static code analysis to identify all unserialize() calls without the allowed_classes restriction
• Deploy web application firewall (WAF) rules to detect serialized PHP object patterns in request parameters
• Monitor application logs for PHP object injection signatures and unexpected class instantiation errors
• Conduct regular code audits focusing on deserialization patterns, especially after plugin installations or code updates

Monitoring Recommendations

• Enable detailed logging for the Gearman worker processes and changelog controller actions
• Configure intrusion detection systems to alert on suspicious serialized data patterns in application traffic
• Implement database monitoring to detect modifications to changelog data containing serialized objects
• Set up file integrity monitoring on critical openITCOCKPIT installation directories

How to Mitigate CVE-2026-24892

Immediate Actions Required

• Upgrade openITCOCKPIT to version 5.4.0 or later, which contains the security fix for this vulnerability
• Review and audit any custom plugins or modifications that may interact with changelog or Gearman worker functionality
• Implement network segmentation to limit exposure of the openITCOCKPIT monitoring infrastructure
• Conduct a security review of database contents to ensure no malicious serialized objects have been introduced

Patch Information

The vulnerability has been addressed in openITCOCKPIT version 5.4.0. The fix modifies the unserialize() calls in both GearmanWorkerCommand.php and ChangelogsController.php to include the ['allowed_classes' => false] option, preventing PHP object instantiation during deserialization.

For detailed information about the fix, refer to:

• GitHub Security Advisory GHSA-g83p-vvjm-g39x
• openITCOCKPIT 5.4.0 Release Notes

Workarounds

• If immediate upgrade is not possible, consider implementing application-level input validation for changelog data
• Deploy a reverse proxy or WAF to filter incoming requests containing serialized PHP object patterns
• Restrict network access to the openITCOCKPIT interface to trusted IP ranges only
• Disable or limit access to changelog functionality until the patch can be applied

# Example: Restrict access to openITCOCKPIT interface via iptables
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Example: Backup database before upgrade
mysqldump -u root -p openitcockpit > openitcockpit_backup_$(date +%Y%m%d).sql

# Upgrade to patched version
apt-get update && apt-get install openitcockpit