CVE-2026-57738: 777 Triple-Seven Object Injection Flaw

CVE-2026-57738 Overview

CVE-2026-57738 is a PHP Object Injection vulnerability in the axiomthemes 777 (Triple Seven) WordPress theme. The flaw stems from insecure deserialization of untrusted data [CWE-502] and affects all versions from n/a through 1.13.0. An unauthenticated attacker can send crafted serialized payloads over the network to trigger object injection in the theme's PHP runtime. Successful exploitation can lead to arbitrary code execution, data tampering, and full site compromise depending on the PHP classes (gadgets) loaded on the target WordPress instance.

Critical Impact
Unauthenticated network-based object injection in the axiomthemes 777 theme (≤ 1.13.0) can lead to remote code execution and full WordPress site takeover.

Affected Products

axiomthemes 777 (Triple Seven) WordPress Theme — all versions up to and including 1.13.0
WordPress sites running the vulnerable theme with PHP gadget chains available (core, plugins, or theme dependencies)
Any hosting environment exposing the theme's request handlers to unauthenticated network traffic

Discovery Timeline

2026-07-13 - CVE-2026-57738 published to NVD
2026-07-13 - Last updated in NVD database

Technical Details for CVE-2026-57738

Vulnerability Analysis

The 777 theme passes attacker-controllable input into a PHP deserialization sink such as unserialize() without validating or restricting the resulting object types. When PHP reconstructs the serialized payload, magic methods like __wakeup(), __destruct(), or __toString() execute automatically on the instantiated objects. If any loaded class within WordPress core, an active plugin, or a theme dependency exposes exploitable behavior in those magic methods, the attacker can chain them into a PHP Object Injection (POI) attack.

The attack vector is network-based, requires no authentication, and needs no user interaction. Impact depends on available gadget chains but typically enables arbitrary file writes, arbitrary file reads, SQL manipulation, or remote code execution. The vulnerability is tracked with an EPSS probability of 0.386% (percentile 31.0) as of 2026-07-20.

Root Cause

The root cause is unsafe deserialization of untrusted input inside the theme's request-processing logic. The code invokes PHP's native deserialization on data derived from HTTP parameters, cookies, or stored options without integrity checks, type allow-listing, or use of safer formats such as JSON.

Attack Vector

An attacker crafts a serialized PHP object payload targeting a known gadget chain (for example, chains present in common WordPress plugins or libraries). The payload is delivered via an HTTP request parameter processed by the vulnerable theme code path. When PHP deserializes the payload, the gadget chain executes, giving the attacker code execution in the context of the web server user. See the Patchstack WordPress Vulnerability Report for advisory details.

Detection Methods for CVE-2026-57738

Indicators of Compromise

HTTP requests containing serialized PHP payload markers such as O: (object), a: (array), or s: (string) in query strings, POST bodies, or cookies targeting theme endpoints
Unexpected PHP processes spawning shell commands or writing to wp-content/uploads/ and other writable paths
New or modified PHP files under the themes/triple-seven/ or wp-content/ directories
Outbound network connections from the web server to unfamiliar IPs shortly after suspicious POST requests

Detection Strategies

Inspect web server access logs for URI parameters containing serialized PHP patterns (O:\d+:", __PHP_Incomplete_Class)
Deploy a Web Application Firewall (WAF) rule set that flags PHP serialization signatures against WordPress theme endpoints
Enable PHP open_basedir and error logging to surface unexpected class instantiation or file access anomalies
Perform integrity monitoring on theme and plugin files to catch post-exploitation webshell drops

Monitoring Recommendations

Alert on PHP-FPM or php-cgi processes spawning sh, bash, curl, wget, or python as child processes
Correlate WordPress wp_options and user table modifications with recent inbound HTTP requests to theme paths
Monitor for administrative user creation events not tied to legitimate console activity
Track egress traffic from web server hosts and alert on connections to non-approved destinations

How to Mitigate CVE-2026-57738

Immediate Actions Required

Identify all WordPress installations running the axiomthemes 777 (Triple Seven) theme at version 1.13.0 or earlier
Deactivate and remove the vulnerable theme on affected sites until a fixed version is verified from the vendor
Apply WAF rules that block PHP serialized object patterns in HTTP requests to the affected sites
Rotate WordPress secrets in wp-config.php (AUTH_KEY, SECURE_AUTH_KEY, etc.) and reset administrator credentials if compromise is suspected

Patch Information

At the time of publication, no fixed version is listed in the NVD entry for CVE-2026-57738. Consult the Patchstack WordPress Vulnerability Report for the latest vendor guidance and update to any release above 1.13.0 once axiomthemes publishes a patched build.

Workarounds

Switch affected sites to a maintained theme until an official patch is released by axiomthemes
Restrict access to the WordPress site via IP allow-listing or authentication at the reverse proxy while remediation is in progress
Enable virtual patching through Patchstack or a comparable WAF service that ships a specific rule for this CVE
Disable PHP unserialize() on untrusted input by auditing custom theme code and replacing with json_decode() where feasible

bash

# Configuration example: block serialized PHP object payloads at the WAF (ModSecurity)
SecRule ARGS|REQUEST_COOKIES|REQUEST_BODY "@rx O:[0-9]+:\"[a-zA-Z_\\\\]+\":[0-9]+:" \
  "id:1057738,\
   phase:2,\
   deny,\
   status:403,\
   msg:'Potential PHP Object Injection (CVE-2026-57738) blocked',\
   tag:'CVE-2026-57738',\
   tag:'CWE-502'"