Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Scope (S:U) | Scope unchanged |
| Confidentiality (C:H) | High confidentiality impact |
| Integrity (I:H) | High integrity impact |
| Availability (A:H) | High availability impact |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
About Gravity Forms
CVE-2026-103039 affects Gravity Forms. Before acting, confirm where Gravity Forms runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: The Gravity Forms plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 3.1.2 via a Post Custom Field whose input type is List. This is due to GFFormsModel::create_post() passing the submitted value to WordPress' unrestricted global maybe_unserialize() rather than the plugin's own hardened GFCommon::maybe_unserialize(), which was added in 3.1.1 and passes allowed_classes => false precisely to prevent object instantiation. Where the field has a content template enabled, the submitted row reaches that call verbatim. This makes it possible for unauthenticated attackers to inject a PHP object into post meta. No PHP Object Injection gadget chain is present in the plugin itself; however, if a gadget chain is present via an additional plugin or theme, it could allow the attacker to perform actions such as remote code execution. Where the custom field is mapped to the protected _wp_page_template meta key, WordPress itself supplies the chain: validate_file() accepts non-scalars, WP_Theme::__toString() then resolves an attacker-controlled path, and on hosts with a readable PEAR install and register_argc_argv enabled this yields remote code execution.
The weakness class is Deserialization of Untrusted Data. The application rebuilds objects from attacker controlled data, which can run code.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Gravity Forms |
| Affected versions | See the vendor advisory under Technical References |
| Published | Oct 30, 2026 |
| Last modified | Oct 30, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | security@wordfence.com |
How to detect it
- Inventory every instance of Gravity Forms and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Gravity Forms named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Gravity Forms to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-502: Deserialization of Untrusted Data More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
Dell ObjectScale, versions prior to 4.4.0.0, contains a Deserialization of Untrusted Data vulnerability. An unauthenticated attacker with remote access could potentially exploit this vulnerability, leading to Remote execution.
Altec DocLink (now maintained by Beyond Limits Inc.) version 4.0.336.0 exposes insecure .NET Remoting endpoints over TCP and HTTP/SOAP via Altec.RDCHostService.exe using the ObjectURI "doclinkServer.soap". The service does not require authentication and is vulnerable to unsafe object unmarshalling, allowing remote attackers to read arbitrary files from the underlying system by specifying local file paths. Additionally, attackers can coerce SMB authentication via UNC paths and write arbitrary files to server locations. Because writable paths may be web-accessible under IIS, this can result in unauthenticated remote code execution or denial of service through file overwrite.
Joomla Extension - aimy-extensions.com - RCE via PHP object injection in Aimy Captcha-Less Form Guard 18.0 - 20.0 - A forged clfgd field allows PHP objection injection and thereby remote code execution.
Calero VeraSMART versions prior to 2022 R1 expose an unauthenticated .NET Remoting HTTP service on TCP port 8001. The service publishes default ObjectURIs (including EndeavorServer.rem and RemoteFileReceiver.rem) and permits the use of SOAP and binary formatters with TypeFilterLevel set to Full. An unauthenticated remote attacker can invoke the exposed remoting endpoints to perform arbitrary file read and write operations via the WebClient class. This allows retrieval of sensitive files such as WebRoot\\web.config, which may disclose IIS machineKey validation and decryption keys. An attacker can use these keys to generate a malicious ASP.NET ViewState payload and achieve remote code execution within the IIS application context. Additionally, supplying a UNC path can trigger outbound SMB authentication from the service account, potentially exposing NTLMv2 hashes for relay or offline cracking.
Deserialization of untrusted data in Microsoft Planetary Computer Pro allows an unauthorized attacker to disclose information over a network.
Deserialization of untrusted data in Microsoft Bing allows an unauthorized attacker to execute code over a network.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-103039 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications