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Omnisend WordPress Plugin CVE-2026-97074

| EUVDEUVD-2026-89894 MEDIUM
Authorization Bypass Through User-Controlled Key (CWE-639)
2026-09-30 Patchstack GHSA-px7h-jc96-f274
4.3
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 low-privilege Subscriber account
  2. Delivery
    Identify plugin endpoint with object ID
  3. Exploit
    Substitute another user's object reference
  4. Execution
    Server skips ownership check
  5. Impact
    Modify unauthorized data (integrity impact)

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Object-level authorization, IDOR prevention
Exploitation Conditions

Exploitation requires an authenticated WordPress account at Subscriber level or higher on a site running Omnisend Newsletters, Email Marketing, SMS and Popups plugin version 1.9.0 or earlier (PR:L). No user interaction is needed (UI:N) and the request is remote/network-based (AV:N). The limiting factors are the authentication requirement (a valid low-privilege account must exist, which on sites allowing open registration is trivial but on closed sites is a barrier) and the narrow impact ceiling - only integrity of specific objects is affected (I:L), with no confidentiality or availability consequences. The exact affected endpoint/parameter is not disclosed in available data.

Impact

The composite signals point to a low-to-moderate real-world priority. The provided CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N, base 4.3) describes a network-reachable, low-complexity flaw but requires authenticated low-privilege access (PR:L, described as Subscriber level) and yields only a limited integrity impact (I:L) with no confidentiality (C:N) or availability (A:N) effect. No EPSS score, no CISA KEV listing, and no public proof-of-concept were provided, so there is no public exploit identified at time of analysis and no evidence of active exploitation. The CWE-639 (IDOR) classification is consistent with an authenticated user manipulating an object reference to alter data they should not own. The single Patchstack reference is the only corroborating source and does not name the exact parameter or endpoint. One notable metadata conflict: the description and tags label this an 'Authentication Bypass,' but the vector (PR:L) and CWE-639 make this an authorization/IDOR issue, not authentication bypass - the attacker must already be authenticated. Net: a real but low-severity authenticated integrity issue, not a high-urgency remote-code or data-breach event.

Exploit ScenarioDerived

An attacker registers or obtains a low-privilege Subscriber account on a WordPress site running the Omnisend plugin (<=1.9.0), then sends a request to an affected plugin endpoint while substituting an object identifier (ID) that belongs to another user or resource. Because the plugin fails to verify ownership of the referenced object, the attacker modifies data they should not control (integrity impact only). No public PoC was provided, and exploitation requires an authenticated account.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 30, 2026

Subscriber-level insecure direct object reference (IDOR) in the Omnisend WordPress plugin through version 1.9.0 allows an authenticated low-privilege user (Subscriber or higher) to modify certain objects they do not own. The flaw is rated CVSS 4.3 with a limited integrity-only impact, requires no user interaction, and can be reached remotely; no public exploit was identified at time of analysis. Sites running the plugin 1.9.0 or earlier with open registration are at higher practical risk because obtaining the required Subscriber account is trivial.

RemediationAI

No vendor-released patch identified at time of analysis for CVE-2026-97074; monitor the Patchstack advisory (https://patchstack.com/database/wordpress/plugin/omnisend/vulnerability/wordpress-newsletters-email-marketing-sms-and-popups-by-omnisend-plugin-1-9-0-insecure-direct-object-references-idor-vulnerability?_s_id=cve) for a fixed plugin version and update immediately once available. Until a patched release is confirmed, consider temporarily deactivating the Omnisend plugin if its newsletter/SMS/popup features are non-critical, which removes the attack surface but disables marketing functionality. If deactivation is not acceptable, restrict the ability to obtain a low-privilege Subscriber account by disabling open user registration or requiring administrator approval, and audit or remove unused Subscriber accounts; this raises the bar but may affect legitimate site users. Apply WAF or virtual patching rules to block unauthorized object-reference patterns against Omnisend plugin endpoints (such as wp-admin/admin-ajax.php actions and REST routes used by the plugin), but test carefully because overly broad rules can break legitimate newsletter or popup operations. Keep WordPress, all plugins, and themes up to date, and review role capabilities so Subscribers cannot access plugin administrative functions.

Affected VersionsENISA

Newsletters, Email Marketing, SMS and Popups by Omnisend n/a ≤1.9.0

Affected Packages

euvd newsletters_email_marketing_sms_and_popups_by_omnisend 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 issue is CWE-639 (Authorization Bypass Through User-Controlled Key), a class of IDOR where a plugin endpoint accepts an object identifier from the request and fails to verify that the authenticated user is authorized to act on that object. The affected component is the WordPress plugin 'Newsletters, Email Marketing, SMS and Popups by Omnisend', which integrates WordPress with Omnisend marketing features such as newsletters, email campaigns, SMS, and popups. CPE data lists cpe:2.3:a:omnisend:newsletters,_email_marketing,_sms_and_popups_by_omnisend:*:*:*:*:*:*:*:* as affected, while the advisory and description scope the vulnerable range to <= 1.9.0. Because the CVSS vector is AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N, the root cause is an authorization check gap rather than a memory-safety or injection bug; the attacker must already have a valid low-privilege account, and successful exploitation only tampers with data integrity of targeted objects, with no confidentiality or availability loss. The exact endpoint and parameter are not disclosed in available data.

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Severity by source

Vendor (Patchstack) PRIMARY 4.3 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
vuln.today AI 4.3 MEDIUM

Network-reachable IDOR needing an authenticated Subscriber account (PR:L) with no user interaction; missing ownership check permits limited unauthorized data modification (I:L only).

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

Primary rating from Vendor (Patchstack).

CVSS VectorVendor: Patchstack

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

DescriptionCVE.org

Subscriber Insecure Direct Object References (IDOR) in Newsletters, Email Marketing, SMS and Popups by Omnisend <= 1.9.0 versions.

Threat Intelligence Overview

EPSS Score
0.3%
Top 85% exploitable
Prevalence
Medium
Omnisend is a widely-installed WordPress email-marketing plugin
Data Quality
3 sources
Confidence: Low

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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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