CVE-2026-40877

Executive Summary

CVE-2026-40877 is a PHP object injection vulnerability in Combodo iTop, a web-based IT service management (ITSM) platform, affecting versions prior to 3.2.3. The vulnerability resides in the user preference functionality and can be leveraged by an authenticated attacker to achieve remote code execution on the underlying server. With a CVSS score of 8.7, this flaw poses a significant risk to organizations running vulnerable iTop deployments, particularly those exposed to the internet or accessible by lower-privileged users. The issue has been addressed in iTop version 3.2.3, but no public exploit code or patch evidence from independent sources has been identified at this time.

Technical Analysis

The vulnerability is classified under CWE-94 (Improper Control of Generation of Code: Code Injection) and specifically manifests as a PHP object injection flaw within the user preference mechanism of Combodo iTop. PHP object injection occurs when user-supplied input is passed to an unsafe unserialize() call (or an equivalent deserialization function) without proper validation or sanitization. When crafted data is deserialized, it can instantiate arbitrary PHP objects of classes that exist within the application's codebase.

The attack surface is the user preference functionality, which is accessible to any authenticated user of the iTop platform. Since iTop is a multi-user IT service management tool, even low-privileged accounts (e.g., support agents or portal users) can reach this functionality. The vulnerability chain typically requires a "magic method" (such as __destruct, __wakeup, or __toString) in an available class to be triggered during or after deserialization. If such a gadget exists in the iTop codebase or its dependencies, an attacker can chain the object injection into arbitrary code execution.

The CVSS vector AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N reveals several important characteristics:

• Attack Vector (AV:N): The vulnerability is exploitable over the network.
• Attack Complexity (AC:L): No special conditions or race conditions are needed.
• Privileges Required (PR:L): The attacker needs valid low-privileged credentials.
• User Interaction (UI:R): A user action is required — likely an administrator or another user performing an action that processes the crafted data within the preference context.
• Scope (S:C): A compromise in the vulnerable component impacts resources beyond its security scope (e.g., the underlying operating system).
• Confidentiality/Integrity Impact (C:H/I:H): Full compromise of confidentiality and integrity; no availability impact is scored.

While the NVD description does not provide specific technical details about the exact parameters, file paths, or gadget chains involved, the vulnerability class is well understood. PHP object injection typically requires the attacker to submit a serialized payload through a parameter that the application later deserializes, often via a cookie, form field, or API request. The lack of public exploit code suggests that either the vulnerability was recently disclosed or the specific gadget chain required for code execution has not yet been publicly documented.

Exploitation Scenarios

While no public PoC exists, the attack chain can be inferred from the vulnerability class and the NVD description. The following scenario outlines the likely mechanism:

Step 1 — Reconnaissance and Target Identification: An attacker identifies an internet-facing Combodo iTop instance by searching for default login pages ("itop/login", "pages/UI.php", or similar patterns). Shodan and other search engines can identify these services via HTTP banner detection. The attacker also checks the version number disclosed on the login page or via version-specific static resources to confirm the target runs a version prior to 3.2.3.

Step 2 — Authentication and Flaw Triggering: The attacker authenticates using valid low-privileged credentials (e.g., a standard user or support agent account, possibly obtained via credential stuffing or previous phishing). Once authenticated, the attacker navigates to the user preference section of the web interface. The attacker crafts a malicious serialized PHP object — for example, O:27:"SomeClass":1:{s:...} — and submits it within the preference update request. If the application does not properly validate the input before passing it to unserialize(), the crafted string is accepted and stored or immediately processed.

Step 3 — Object Deserialization and Code Execution: When the application deserializes the attacker's payload, the PHP engine instantiates the specified class. If a magic method (e.g., __destruct or __wakeup) is defined in that class and has side effects (writes files, executes commands, includes files), the attacker achieves arbitrary code execution. For example, using a class that writes a PHP webshell to the web root or a class that invokes system() or eval() within a magic method. The user interaction (UI:R) component in the CVSS vector likely reflects the requirement that an administrator subsequently views or processes the user's preferences, triggering the deserialization on the server.

Step 4 — Post-Exploitation: With remote code execution as the web application user (typically www-data or apache), the attacker can enumerate the server, attempt privilege escalation to root, access database credentials stored in configuration files, exfiltrate sensitive IT service management data (tickets, asset inventories, credentials), and pivot to other systems within the internal network. The high confidentiality and integrity impact scores reflect the potential for full data theft and system modification.

Impact Assessment

The business impact of CVE-2026-40877 is severe for any organization relying on Combodo iTop as its ITSM platform. The CVSS score of 8.7 (High) reflects the combination of network exploitability, low privilege requirement, and full confidentiality/integrity compromise with a scope change.

Business Impact:

• Data Breach Risk: iTop stores tickets, service requests, CI (configuration item) information, user data, and potentially contains credentials or references to internal systems. Successful exploitation exposes this data.
• Lateral Movement: Since iTop often integrates with other tools (LDAP/AD, email servers, monitoring systems via REST APIs), a compromised instance serves as a pivot point for internal network infiltration.
• Business Continuity: While availability is not directly scored (A:N), an attacker achieving code execution can disrupt operations by tampering with ticketing workflows, deleting records, or deploying ransomware.
• Compliance: If the affected data includes PII or regulated data (e.g., device information, user accounts), the organization may face regulatory reporting obligations.

Affected Systems: All Combodo iTop deployments running versions prior to 3.2.3. This includes standalone installations, Docker containers, and managed deployments. The MySQL/MariaDB database used by iTop may also be indirectly impacted if the attacker leverages the code execution to extract database credentials.

Blast Radius: The scope change (S:C) in the CVSS vector indicates that the impact extends beyond the web application process. An attacker achieving code execution can access the operating system, other files, network shares, and services running on the same host, potentially expanding the compromise to the entire server and connected backends.

Detection Guidance

Sigma Rule

title: Combodo iTop PHP Object Injection Attempt
id: 7a1d5090-2c1e-4b5a-9d6f-3c8e4a2d0b51
status: experimental
description: Detects attempts to exploit CVE-2026-40877 — PHP object injection in user preferences (serialized payloads in preference parameters)
author: Valtersit Threat Intel
date: 2026/02/14
logsource:
    category: webserver
    product: apache
    detection:
        selection_method:
            cs-method: POST
        selection_url:
            cs-uri-query|contains:
                - 'preference'
                - 'profile'
                - 'user'
        selection_payload:
            cs-body|contains:
                - 'O:'
                - 's:'
                - 'unserialize'
            condition: selection_method and selection_url and selection_payload
    falsepositives:
        - Legitimate serialized data in user preferences (rare)
    level: high

YARA Rule

rule CVE_2026_40877_Combodo_iTop_PHP_Object_Injection
{
    meta:
        author = "Valtersit Threat Intel"
        description = "Detects PHP object injection payloads targeting Combodo iTop user preferences (CVE-2026-40877)"
        date = "2026-02-14"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-40877"
        score = 87
    strings:
        $serialized_object = /O:[0-9]+:"[^"]+":[0-9]+:/
        $serialized_short = /O:\d+:"\w+":\d+:\{/
        $preference_param = "serialized_prefs" nocase
        $preference_field = "preferences" nocase
        $magic_destruct = "__destruct" nocase
        $magic_wakeup = "__wakeup" nocase
        $php_function = /(system|exec|passthru|shell_exec|eval)\s*\(/ nocase
    condition:
        uint16(0) == 0x0A0D or filesize < 10MB and
        (1 of ($serialized_*) and 1 of ($magic_*) and 1 of ($php_function))
        or ($serialized_object and $preference_param) or ($serialized_object and $preference_field)
}

Suricata IDS Rule

alert http any any -> $HOME_NET any (msg:"CVE-2026-40877 - Combodo iTop PHP Object Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"preference"; http_uri; nocase; pcre:"/O:[0-9]+:\"[^\"]+\":[0-9]+:/Ui"; classtype:attempted-admin; sid:202640877; rev:1; metadata:created_at 2026_02_14, cve CVE-2026-40877;)

Elastic Detection

sequence by host.name
  [network where event.action == "connection_established"
   and destination.port == 443
   and process.executable != null]
  [http where event.action == "post"
   and url.path like "*preference*"
   and body like "O:*"
   and body like "s:*"]

Splunk SPL Query

index=web sourcetype=access_combined
| where method="POST"
| search uri="*preference*" OR uri="*profile*"
| regex _raw="O:[0-9]+:\"[^\"]+\":[0-9]+:"
| table _time, src_ip, uri, host, status
| sort - _time

Wazuh OSSEC Rule

<group name="combodo_itop,">
  <rule id="100877" level="12">
    <decoded>preference</decoded>
    <match>O:[0-9]+:"</match>
    <description>Potential PHP Object Injection in Combodo iTop user preferences (CVE-2026-40877)</description>
    <group>vulnerability,</group>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED (no patch evidence from tracked sources beyond the vendor's release).

1) Immediate Mitigations (to apply before patching):

• Restrict Network Access: Ensure iTop is not directly exposed to the internet. Place it behind a VPN, bastion host, or firewall with access control lists. If internet access is required, use a reverse proxy with Web Application Firewall (WAF) rules to inspect for serialized PHP payloads.
• Enforce Strong Authentication: Disable default accounts, enforce MFA for all iTop users, and review user accounts for stale/unused credentials. Given the low privilege requirement (PR:L), minimize the number of users with access to the system.
• Disable Unused Features: If the user preference functionality is not essential for all user types, restrict access via role-based permissions in iTop administration.
• Monitor Logs: Deploy the detection rules provided above and alert on any anomalies involving serialized payloads in preference updates.

2) Patch/Upgrade Steps:

• Upgrade Combodo iTop to version 3.2.3 or later. The vendor has confirmed the fix is included in version 3.2.3.
• Verify the version after upgrade via the "About" page or version endpoint.
• Follow the official upgrade documentation, including database schema updates (back up the database first).
• Test the upgraded instance in a staging environment before production rollout.

3) Long-Term Hardening:

• Maintain a regular patching schedule for iTop and its dependencies (PHP, MySQL, web server).
• Follow the principle of least privilege for all iTop user accounts; review role definitions periodically.
• Deploy a Web Application Firewall (WAF) with rules for PHP object injection (OWASP CRS ruleset).
• Segregate the iTop server from other internal services; apply network segmentation.
• Implement application-level input validation, especially for serialization functions; consider converting to JSON-based serialization.
• Enable comprehensive logging and integrate with SIEM for continuous monitoring.
• Subscribe to Combodo security announcements and monitor CVE feeds for new disclosures.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-40877
2. Combodo Official Site: https://www.combodo.com/ (vendor advisory for version 3.2.3 release notes)
3. iTop Download Page: https://www.combodo.com/itop (for obtaining the patched version)
4. CWE-94 Definition: https://cwe.mitre.org/data/definitions/94.html
5. ATT&CK T1190: https://attack.mitre.org/techniques/T1190/

Threat Actor Campaign Notes

As of the report date, no known threat actor campaigns have been observed exploiting CVE-2026-40877, and the vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. No evidence of in-the-wild exploitation has been documented. The absence of public exploit code increases the likelihood of a delayed exploitation window, but given the CVSS score of 8.7 and the prevalence of iTop in enterprise environments, we assess a high probability of weaponization within 60–90 days once patch details become widely known. Security teams are strongly advised to prioritize patching and implement the detection rules provided above.