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Relevanssi CVE-2026-114704

| EUVDEUVD-2026-109297 HIGH
Deserialization of Untrusted Data (CWE-502)
2026-10-24 audit@patchstack.com GHSA-q53w-3673-wrjv
7.2
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
    Obtain high-privilege WordPress account
  2. Delivery
    Submit crafted serialized payload to vulnerable input
  3. Exploit
    Trigger PHP object injection on unserialize
  4. Execution
    Invoke POP gadget chain
  5. Impact
    Full compromise of site data and integrity

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

Requires an authenticated attacker with high privileges (CVSS PR:H) - in a WordPress context this is effectively administrator-level access to the site running Relevanssi version 4.28.4 or earlier. The specific feature, endpoint, or parameter that deserializes untrusted data is not described in the available sources, and whether a usable POP gadget chain exists (a prerequisite for turning object injection into meaningful impact) is likewise not stated. Limiting factors: the PR:H requirement eliminates unauthenticated and low-privilege attackers, no user interaction is needed once that access is held (UI:N), and the affected version ceiling is 4.28.4.

Impact

The provided CVSS 3.1 vector (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, base 7.2 High) describes a network-reachable, low-complexity flaw with full confidentiality, integrity and availability impact, but gated behind PR:H - high-privilege authentication. That PR:H is the single most important risk-reducer: an attacker already needs high-level (typically administrator-equivalent) access to the WordPress site, which substantially narrows the realistic threat to insider misuse, compromised admin credentials, or chaining from another privilege-granting bug. No EPSS score was supplied, so exploitation probability cannot be quantified. The CVE is not listed in CISA KEV and no proof-of-concept or exploit reference is present in the input - the only reference is a Patchstack advisory database entry, which is an advisory, not exploit code. The vuln.today decision label is 'this_week' (not act_now/emergency), which is consistent with a serious-but-not-actively-exploited authenticated issue. Net: this is a legitimate High-severity deserialization/object-injection bug worth patching promptly, but the PR:H precondition makes it a managed-priority item rather than an emergency; it is not a mass-exploitation-at-the-perimeter scenario on the available signals.

Exploit ScenarioDerived

An attacker who already holds high-privilege (admin-level) access to a WordPress site running Relevanssi 4.28.4 or earlier submits crafted serialized PHP data to a plugin code path that unserializes untrusted input, triggering PHP Object Injection. If a suitable POP gadget chain is available in the plugin, WordPress core, or other installed code, this can escalate to data disclosure, data tampering, or code execution. No public exploit code is identified in the available sources, and the exact triggering parameter or feature is not described.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 24, 2026

PHP object injection in the Relevanssi WordPress plugin through 4.28.4 allows an authenticated attacker with high privileges - effectively administrator-level access in WordPress - to pass untrusted data into a deserialization path, with potential high impact to confidentiality, integrity, and availability. The specific vulnerable feature, endpoint, or parameter is not described in the available sources, and whether a usable POP gadget chain exists is not confirmed. No public exploit was identified at time of analysis.

RemediationAI

No vendor-released patch identified in the available data; the supplied Patchstack advisory is the tracking reference for this issue. Because exploitation requires high-privilege authentication (CVSS PR:H), the directly relevant control is to restrict administrator-level access on sites running Relevanssi 4.28.4 or earlier to trusted operators. If the plugin is not required, deactivating it removes the affected attack surface at the cost of losing Relevanssi search functionality. Monitor the Patchstack advisory for a fixed release and apply it when published.

Affected VersionsENISA

Relevanssi 0 ≤4.28.4

Affected Packages

euvd relevanssi 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

Relevanssi is a WordPress search plugin, and CVE-2026-114704 is classified as CWE-502, Deserialization of Untrusted Data, which can enable PHP object injection. The CVSS 3.1 vector is AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H (base 7.2 High), meaning the flaw is network-reachable and low-complexity but requires high-privilege authentication; no user interaction is required once that access is held. The sources do not describe the specific code path, request parameter, or plugin feature that deserializes untrusted input, and they do not state whether a usable POP gadget chain is present - a prerequisite for turning object injection into meaningful impact. No CPE data was supplied; the affected version ceiling is 4.28.4.

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Severity by source

Vendor (patchstack) PRIMARY 7.2 HIGH
AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.2 HIGH

Network-reachable admin feature (AV:N), but PHP object injection requires high-privilege authenticated access (PR:H); object injection can yield full C/I/A impact, no UI needed.

3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:H/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
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Deserialization of Untrusted Data vulnerability in Christoph Vielgrader Relevanssi relevanssi allows Object Injection.This issue affects Relevanssi : from n/a through 4.28.4.

Executive ViewAI

Why It Matters

A high-severity vulnerability in the Relevanssi WordPress plugin (versions through 4.28.4) permits authenticated administrators to trigger PHP object injection, potentially compromising the confidentiality, integrity, and availability of the entire WordPress site. Since administrator-level access is required, the risk is primarily from insider threats or attackers who have already escalated privileges, but the potential for full site takeover and data exposure warrants management attention.

Business Impact: Medium
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: restrict and monitor administrator access, disable or remove the plugin if non-essential, deploy WAF rules to inspect for serialized payloads, and conduct regular integrity checks of site files and database.

Threat Intelligence Overview

EPSS Score
0.4%
Top 65% exploitable
Prevalence
Medium
popular WordPress search plugin, widely installed but not universal
Social Media
1
Sightings
Data Quality
7 sources
Confidence: High

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 HIGH
CISA KEV No
Public POC No
EPSS 0.4%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
No
Human Impact
Medium
Technical Impact
Total

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
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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