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Relevanssi Premium EUVDEUVD-2026-91249

| CVE-2026-103426 HIGH
Cross-site Scripting (XSS) (CWE-79)
2026-10-02 Wordfence GHSA-64c7-fgwg-hx23
7.2
CVSS 3.1 · Vendor: Wordfence
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Attack ChainAIDerived

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

  1. Access
    Harvest public _rt_nonce from search page
  2. Delivery
    Submit crafted _rt parameter payload
  3. Exploit
    Store XSS via click-tracking logging
  4. Execution
    Victim loads injected page
  5. Impact
    Script executes in victim browser context

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

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

Exploitation Conditions

Exploitation requires the plugin's 'click-tracking and logging' feature to be explicitly activated in Relevanssi Premium settings - a non-default configuration; sites without this feature enabled are not exploitable. When enabled, no authentication is needed (PR:N) because a valid _rt_nonce is publicly emitted on every search-results page, so the nonce provides no real barrier to unauthenticated attackers. Realistic impact is further gated by the stored-XSS delivery model: the payload only executes when a user subsequently accesses the injected page. Affected scope is Relevanssi Premium versions 0 through 2.31.4 inclusive; the free Relevanssi edition and sites on later/patched versions are outside the stated affected range.

Impact

This is a credible, moderately-high priority issue rather than a mere paper tiger, though it falls short of emergency status. The Wordfence-supplied CVSS vector (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N, base 7.2) indicates network-reachable, low-complexity, unauthenticated exploitation with a scope change (script executing in the victim's browser context), and the description reinforces low complexity by noting a valid _rt_nonce is publicly emitted on every search-results page - defeating the one control that would otherwise gate the click-tracking endpoint. No EPSS score, KEV listing, or POC was provided in the input, so there is no public exploit identified at time of analysis and no evidence of active exploitation; the risk is therefore potential rather than demonstrated. The single most important mitigating signal is NOT in the CVSS vector: exploitation requires the non-default 'click-tracking and logging' feature to be enabled, which sharply narrows the realistically vulnerable population. The CVSS impact is also only Low/Low (stored XSS, no availability impact). Net: treat as a real, patch-worthy stored XSS for sites running Relevanssi Premium with click-tracking enabled, but the conditional feature requirement and absence of exploitation evidence argue against treating it as a drop-everything incident.

Exploit ScenarioDerived

On a WordPress site running Relevanssi Premium (≤2.31.4) with click-tracking and logging enabled, an unauthenticated attacker harvests the publicly-emitted _rt_nonce from a normal search-results page, then submits a crafted '_rt' parameter containing a malicious script payload. The payload is stored and later executes in the browser of any user who accesses the injected page, enabling session/cookie theft or actions in the victim's context. No public exploit was identified in the provided data, but the attack is trivially accessible given the nonce exposure and low complexity.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 02, 2026

Stored cross-site scripting in Relevanssi Premium through 2.31.4 lets unauthenticated attackers inject arbitrary web scripts through the '_rt' parameter when the plugin's click-tracking and logging feature is enabled. A valid _rt_nonce is publicly emitted on every search-results page, so the nonce does not stop unauthenticated exploitation, and the payload executes when a user later visits the injected page. No public exploit identified at time of analysis; exploitation requires the non-default click-tracking feature and is therefore not applicable to default-configuration sites.

RemediationAI

No vendor-released patch identified at time of analysis. Until a patched version is available, the most direct mitigation is to disable the click-tracking and logging feature in Relevanssi Premium settings; this removes the vulnerable code path but disables click tracking and logging functionality. If the plugin is not required, deactivate and remove Relevanssi Premium. Monitor the Wordfence advisory (https://www.wordfence.com/threat-intel/vulnerabilities/id/769a39e0-f626-4c48-a1bb-c9f2402b3098?source=cve) and the vendor site (https://www.relevanssi.com/) for a fixed release, then upgrade promptly once a patched version is published. If injection is suspected, review and clean stored content in search/log pages; WAF rules targeting _rt payloads may reduce exposure but are not a substitute for disabling the feature or patching.

Affected VersionsENISA

Relevanssi Premium 0 ≤2.31.4

Affected Packages

euvd relevanssi_premium 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 Premium is a WordPress search plugin. The flaw is CWE-79 (improper neutralization of input during web page generation, commonly cross-site scripting). The '_rt' parameter is handled by the click-tracking/logging feature, and insufficient sanitization and output escaping allow stored script content to be saved and later rendered. The CPE cpe:2.3:a:relevanssi:relevanssi_premium:*:*:*:*:*:*:*:* identifies the premium plugin as the affected component; the independent assessment notes the vulnerable code path is only active when the plugin's click-tracking and logging setting is explicitly enabled. The CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N vector indicates a network-reachable, low-complexity, unauthenticated issue with changed scope and low confidentiality/integrity impact; the _rt_nonce is not an effective barrier because it is publicly exposed on search-results pages. The stored delivery model means script execution depends on a victim accessing the injected page.

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Severity by source

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

Publicly-emitted nonce keeps AC:L and PR:N despite the feature-enabled precondition; stored XSS auto-executes (UI:N) in the victim browser, yielding scope change S:C with Low C/I and no availability impact.

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

Primary rating from Vendor (Wordfence).

CVSS VectorVendor: Wordfence

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

DescriptionCVE.org

The Relevanssi Premium plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the '_rt' parameter in all versions up to, and including, 2.31.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the click-tracking and logging feature to be activated in the plugin settings, and exploitation is trivially accessible to unauthenticated users because a valid _rt_nonce is publicly emitted on every search-results page.

Executive ViewAI

Why It Matters

Relevanssi Premium, a widely deployed WordPress search plugin, contains a stored cross-site scripting flaw in versions through 2.31.4 that can let attackers plant scripts on site pages which then execute in the browsers of visitors and administrators. The exposure is configuration-dependent: it applies only to sites that have enabled the plugin's optional click-tracking and logging feature, while default deployments are not affected. Affected organizations should prioritize identifying which sites run this configuration, because successful exploitation can lead to session theft, credential compromise, and content tampering under the site's trusted domain.

Business Impact: Medium
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: disable the click-tracking and logging feature in Relevanssi Premium, or deactivate the plugin where that feature is not needed; deploy WAF or virtual patching to block script content in the '_rt' parameter; sanitize and monitor stored content for injected scripts; and limit plugin administration to trusted accounts.

Threat Intelligence Overview

EPSS Score
0.2%
Top 87% exploitable
Prevalence
Medium
popular WordPress search plugin, but paid Premium tier narrows footprint
Data Quality
4 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 HIGH
CISA KEV No
Public POC No
EPSS 0.2%
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
Partial

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

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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