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CVE-2026-63030 Google Chronicle · YARA-L

Detect WordPress Core Interpretation Conflict Vulnerability (CVE-2026-63030) in Google Chronicle

WordPress Core contains an interpretation conflict vulnerability (CWE-436) fixed in WordPress 7.0.2, in which differing parsing/interpretation behavior between components of the request-handling pipeline (e.g., PHP, web server, and WordPress core routing/sanitization layers) allows an attacker to smuggle or disguise malicious input so it is treated differently downstream than upstream validation expected. This class of flaw is commonly abused to bypass input filtering, achieve request smuggling-style effects against reverse proxies/CDNs fronting WordPress, or slip malicious payloads (e.g., leading to file write, privilege escalation, or authentication bypass) past security controls that assume a single canonical interpretation of the request. The vulnerability is listed in CISA KEV, indicating confirmed active exploitation in the wild, and is subject to CISA BOD 26-04 remediation timelines for federal and high-risk entities. No CVSS score has been published at time of writing; PoC details are not publicly available, but active exploitation implies working exploit code exists among threat actors. Detection focuses on anomalous WordPress core request patterns consistent with interpretation-conflict abuse: malformed/duplicate headers, ambiguous content-length/transfer-encoding combinations, unusual URL encoding or path traversal-like sequences hitting wp-admin/wp-login/wp-json endpoints, and post-exploitation indicators such as new admin users, unexpected plugin/theme file writes, or webshell drops shortly after anomalous requests.

MITRE ATT&CK

Tactic
Initial Access Defense Evasion Privilege Escalation

YARA-L Detection Query

Google Chronicle (YARA-L)
yaral
rule wordpress_interpretation_conflict_cve_2026_63030 {
  meta:
    author = "df00tech"
    description = "Detects anomalous encoded requests to WordPress core endpoints consistent with CVE-2026-63030 interpretation-conflict exploitation"
    severity = "HIGH"
  events:
    $e.metadata.event_type = "NETWORK_HTTP"
    $e.target.url = /.*(wp-admin|wp-login\.php|wp-json|xmlrpc\.php).*/
    $e.network.http.method = "POST" or $e.network.http.method = "GET"
    re.regex($e.target.url, `%00|%0d%0a|\.\.`)
  match:
    $e.principal.ip over 5m
  condition:
    $e
}
high severity medium confidence

Chronicle UDM rule flagging HTTP requests to WordPress core endpoints containing null-byte, CRLF, or traversal encoded sequences that indicate attempted exploitation of the interpretation-conflict vulnerability.

Data Sources

UDM Network HTTP Events

Required Tables

NETWORK_HTTP

False Positives & Tuning

  • Legitimate REST API automation or mobile app clients hitting wp-json in bursts
  • Security scanners/vulnerability assessment tools generating encoded payloads against wp-admin
  • Third-party plugins that legitimately pass encoded characters in query parameters

Other platforms for CVE-2026-63030


Testing Methodology

Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.

  1. Test 1Simulate encoded null-byte request to wp-login.php

    Expected signal: Web server access log entry for /wp-login.php with query string containing %00 and the source IP of the test host.

  2. Test 2Simulate ambiguous Transfer-Encoding/Content-Length header request

    Expected signal: Web server or WAF log entry showing conflicting Transfer-Encoding and Content-Length headers on a request to /xmlrpc.php.

  3. Test 3Simulate burst of encoded traversal requests to wp-json

    Expected signal: Eight access log entries within a short window from the same source IP hitting /wp-json/ with encoded traversal sequences in the URI.

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