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Qwery WordPress Theme EUVDEUVD-2026-96528

| CVE-2026-78533 CRITICAL
Deserialization of Untrusted Data (CWE-502)
2026-10-10 Patchstack GHSA-pvr3-238r-qr3r
9.8
CVSS 3.1 · Vendor: Patchstack
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Identify site running Qwery <= 3.6.1
  2. Delivery
    Send crafted serialized PHP payload
  3. Exploit
    Trigger unsafe deserialization (CWE-502)
  4. Execution
    Instantiate malicious object via gadget chain
  5. Impact
    Execute code or manipulate data as web user

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A08:2025 - Software or Data Integrity Failures
ASVS 5.0
V1 - Encoding and Sanitization Safe deserialization, type allowlists
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires that a vulnerable Qwery theme (version 3.6.1 or earlier) be installed and active on an internet-reachable WordPress site, and that attacker-controlled input reach a code path performing PHP deserialization of untrusted data. No authentication or user interaction is required (PR:N/UI:N). The key limiting factor is gadget availability: PHP Object Injection yields meaningful impact (RCE, file write, SQL injection) only when an exploitable gadget chain exists in WordPress core, the theme, or installed plugins; absent a usable chain, impact may be reduced. Upgrading beyond 3.6.1 (fixed version not confirmed in provided data) and restricting the affected theme endpoint limit exposure.

Impact

All available severity signals align toward high theoretical risk: the CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N) describes a network-reachable, low-complexity, unauthenticated flaw with full C/I/A impact, consistent with CWE-502 PHP Object Injection that can escalate to remote code execution when an exploitable gadget chain is present in the WordPress stack. However, the exploitability signals are thin: no EPSS probability was provided, the CVE is NOT in CISA KEV, and no public POC is referenced - so there is no public exploit identified at time of analysis and no evidence of active, widespread exploitation. The practical risk of object-injection bugs is also gadget-dependent: impact is 'confirmed' as high by the CVSS vector and Patchstack reporting, but whether full RCE is achievable in a given install depends on available gadget chains in WordPress core, the theme, and co-installed plugins - a factor the raw 9.8 does not capture. Net: a genuinely high-severity, easy-to-attempt flaw that warrants prompt patching, but current real-world exploitation pressure is unconfirmed, and the modest deployment footprint of a premium theme likely keeps exploitation targeted rather than mass-scale.

Exploit ScenarioDerived

A remote, unauthenticated attacker sends a crafted HTTP request to a vulnerable Qwery theme endpoint carrying a malicious serialized PHP payload, which is deserialized by the application. If a suitable gadget chain exists in the WordPress environment, this triggers object injection leading to arbitrary file operations, SQL manipulation, or remote code execution. No public exploit code is referenced, but the AV:N/AC:L/PR:N/UI:N vector means the attack requires no authentication, no user interaction, and little sophistication.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 10, 2026

Unauthenticated PHP object injection in the Qwery WordPress theme (versions 3.6.1 and earlier) allows any remote attacker who can reach an affected site to pass crafted serialized data into a PHP deserialization sink, with no authentication or user interaction required (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, rated 9.8). Because the flaw is CWE-502, real-world impact depends on whether an exploitable PHP gadget chain exists in WordPress core, the theme, or any installed plugin; if such a chain is reachable, the issue can escalate to remote code execution, arbitrary file write, or SQL injection, otherwise impact may be reduced. At the time of analysis there is no confirmed active exploitation (not in CISA KEV) and no public exploit code identified, though the unauthenticated network vector and full C/I/A rating make the theme a high-priority item for any internet-facing WordPress installation running it.

RemediationAI

No vendor-released patched version is confirmed in the provided data - the advisory establishes only that version 3.6.1 is vulnerable, so the fixed release must be verified on the Patchstack advisory (https://patchstack.com/database/wordpress/theme/qwery/vulnerability/wordpress-qwery-theme-3-6-1-php-object-injection-vulnerability?_s_id=cve) or the theme vendor's changelog before relying on it; if a patched build is not yet published, the safest course is to deactivate and remove the Qwery theme entirely and switch to a maintained alternative, accepting the cost of site redesign. If removal is not immediately possible, reduce exposure by deactivating the theme on non-production or non-public sites and, where the theme must stay live on a public site, place the site behind a WAF or reverse proxy rule that blocks requests carrying PHP serialization payloads (patterns such as 'O:<digits>:"' or 'a:<digits>:{' in parameters, cookies, and JSON bodies) - noting that legitimate plugin traffic can occasionally match these patterns and cause false positives that should be baselined first. Because the deserialization primitive only becomes dangerous in the presence of a gadget chain, an interim hardening step is to audit and remove unused or abandoned plugins that supply known PHP gadget classes, which shrinks the attack surface but does not eliminate the underlying flaw. Keep WordPress core and all plugins current, restrict administrative endpoints, and monitor logs for serialized-object payloads until a confirmed fixed theme version is installed.

Affected VersionsENISA

Qwery n/a ≤3.6.1

Affected Packages

euvd qwery no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The Qwery theme, published by AncoraThemes and distributed through the WordPress theme ecosystem, is affected by PHP Object Injection (CWE-502). This class of bug arises when attacker-controlled input is passed to PHP's unserialize() (directly, or indirectly through a library or framework wrapper) without adequate validation, allowing an attacker to instantiate arbitrary PHP objects and control their properties. The CPE string cpe:2.3:a:ancorathemes:qwery:*:*:*:*:*:*:*:* confirms the vendor/product binding but leaves the version wildcarded, so the affected range must be taken from the advisory: all versions up to and including 3.6.1. Exploitability is governed by gadget availability - the deserialization primitive itself only becomes RCE, file write, or SQL injection when a usable magic-method chain (__wakeup, __destruct, __toString, etc.) exists in the loaded WordPress codebase, which is why identical CVSS vectors can yield very different real-world outcomes across sites with different plugin sets. The CVSS 3.1 vector supplied with the advisory describes the worst-case, gadget-present scenario.

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Severity by source

Vendor (Patchstack) PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 9.8 CRITICAL

Unauthenticated network-reachable deserialization with no user interaction (AV:N/AC:L/PR:N/UI:N); object injection can yield full code execution giving high C/I/A.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (Patchstack).

CVSS VectorVendor: Patchstack

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Unauthenticated PHP Object Injection in Qwery <= 3.6.1 versions.

Executive ViewAI

Why It Matters

The Qwery WordPress theme, used by organizations for their public websites, contains a critical unauthenticated PHP object injection vulnerability (CVE-2026-78533) that could allow attackers to compromise the site and potentially the underlying server. No public exploit identified at time of analysis, and no vendor-released patch identified at time of analysis, but with a CVSS score of 9.8, this poses a high risk to organizational reputation and data security. Immediate mitigation steps are required to protect affected sites.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include deploying a Web Application Firewall (WAF) with rules to block PHP object injection attempts targeting the Qwery theme, disabling the theme if not essential, restricting network access to affected sites, and monitoring for exploitation indicators. Virtual patching via security vendors may also be available.

Threat Intelligence Overview

EPSS Score
0.3%
Top 75% exploitable
Prevalence
Low
premium AncoraThemes WordPress theme, limited commercial install base
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
High
Technical Impact
Total

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.

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