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WPO365 Graph Mailer EUVDEUVD-2026-114654

| CVE-2026-107759 HIGH
Cross-site Scripting (XSS) (CWE-79)
2026-10-31 Wordfence GHSA-jg4v-r26p-p7r2
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
    Submit crafted form subject unauthenticated
  2. Delivery
    Payload forwarded via wp_mail/PHPMailer
  3. Exploit
    Stored unescaped in Graph Mailer log
  4. Execution
    Admin opens affected page
  5. Impact
    Script executes in admin 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

Requires the WPO365 Graph Mailer to be enabled while OAuth authorization has NOT been completed - described as the default state immediately after plugin activation - and requires a mail-sending feature that forwards a submitter-controlled subject to the mailer (e.g., an active Contact Form 7 form reachable by the public). Exploitation is limited by these factors: a site that has completed OAuth configuration or that exposes no subject-forwarding form is not exposed via this path, and the payload only executes when a user (likely an administrator reviewing the mail log/injected page) actually accesses the affected page.

Impact

Multiple signals point to a moderate-but-real priority rather than an emergency. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N, base 7.2) is attacker-favorable on reachability - network-reachable, low complexity, no privileges, with a scope change reflecting script execution in a victim's browser context - but impact is capped at C:L/I:L/A:N, typical of stored XSS. The vuln.today decision label is 'this_week', not act_now/emergency, which is consistent with that profile. No EPSS probability was supplied, there is no CISA KEV listing (so this is NOT confirmed actively exploited), and no public exploit identified at time of analysis - the references are the Wordfence advisory and WordPress trac source-code/changeset links, not working exploit code. A notable nuance: although PR:N implies unauthenticated injection, exploitation is conditioned on the Graph Mailer being enabled while OAuth authorization has not been completed; the description states this is the default state immediately after activation, which supports the unauthenticated rating but also means fully-configured sites may not be exposed. Net: treat as a prompt patch-this-week item, not a drop-everything emergency; the absence of EPSS and the conditional trigger state are the main gaps to verify.

Exploit ScenarioDerived

An attacker submits a public form (e.g., Contact Form 7) on a WordPress site running WPO365 Graph Mailer that is enabled but not yet OAuth-authorized, placing a JavaScript payload in the submitter-controlled subject field. The unsanitized subject is stored and later rendered unescaped (e.g., in the plugin's mail log), executing in the browser of a user - typically an administrator - who views the injected page. No public exploit code is referenced; only the vendor advisory and source-code links exist.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 31, 2026

Stored cross-site scripting in the WPO365 | Microsoft 365 Graph Mailer WordPress plugin, affecting all versions up to and including 6.2, lets unauthenticated attackers plant arbitrary script in a mail subject that is stored and later rendered back to a viewer. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N, 7.2) reflects unauthenticated network reach with a scope change and limited confidentiality and integrity impact. Exploitation is conditional: the Graph Mailer must be enabled while OAuth authorization has not been completed - the default state right after activation - and the site must expose a mail-sending feature that forwards a submitter-controlled subject, such as a public Contact Form 7 form; the injected script only runs when a user, likely an administrator reviewing the mail log or the affected page, actually opens it. No confirmed public exploit code and no CISA KEV listing were identified at time of analysis; the vuln.today decision label is this_week, so this is a moderate-but-real priority rather than an emergency.

RemediationAI

Vendor-released patched version is not independently confirmed from the available data; the references point to a plugin repository changeset (3752919) against the wpo365-msgraphmailer plugin, so treat this as an upstream fix that should be validated against the plugin's current tagged release before relying on it, and check the Wordfence advisory at https://www.wordfence.com/threat-intel/vulnerabilities/id/d51ba0c2-588d-4241-977a-9649cb77c78e?source=cve for the fixed version. Where an immediate update is not possible, the assessment identifies two conditions that close this path: complete the OAuth authorization for Graph Mailer so the plugin is no longer in its unconfigured post-activation state and mail is no longer retained for local rendering, and remove or disable any publicly reachable mail-sending feature that forwards a submitter-controlled subject, such as Contact Form 7 forms, until the plugin is patched. Both carry operational trade-offs - finishing OAuth setup requires tenant-side consent and changes mail routing behavior, while disabling subject-forwarding forms interrupts legitimate contact channels - and neither substitutes for installing the fixed plugin release once it is confirmed.

Affected VersionsENISA

WPO365 | MICROSOFT 365 GRAPH MAILER 0 ≤6.2

Affected Packages

euvd wpo365_microsoft_365_graph_mailer 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 flaw is a classic CWE-79 injection pattern split across input handling and output rendering in a WordPress plugin. The plugin hooks into wp_mail/PHPMailer through Mail/Mailer.php and forwards message metadata - including the subject supplied by whoever submits a form - into its own Graph Mailer pipeline. Per the supplied references, the affected code paths include the mailer itself (Mail/Mailer.php#L71), the logging service (Services/Log_Service.php#L80), and script/style helpers (Core/Script_Helpers.php#L142) plus Ajax_Service.php#L284 and a bundled wizard script, which together indicate that the tainted subject is persisted and then surfaced into an administrative interface without adequate escaping. The trigger depends on deployment state rather than a single request: when Graph Mailer is enabled but OAuth authorization has not yet been completed, mail is not relayed to Microsoft Graph and instead lands in the plugin's own logging/queue view, where the stored subject is rendered. The available sources do not describe further mechanism detail such as the exact escaping routine or the precise rendering sink beyond these files. Sites that have completed OAuth configuration, or that expose no subject-forwarding form, are not reachable through this path according to the assessment.

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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

Unauthenticated remote injection via a public-form subject in the default post-activation state (PR:N/AC:L); stored XSS runs in a victim browser, so S:C with C:L/I:L and A:N.

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:L/VI:L/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 WPO365 | MICROSOFT 365 GRAPH MAILER plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'Subject (via wp_mail/PHPMailer, e.g. CF7 your-subject)' parameter in all versions up to, and including, 6.2 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. The payload is stored without authentication via any mail-sending feature that forwards a submitter-controlled subject (e.g. a Contact Form 7 form) when the Graph Mailer is enabled but OAuth authorization has not been completed, a default state immediately after plugin activation.

Executive ViewAI

Why It Matters

CVE-2026-107759 is a high-severity stored cross-site scripting vulnerability in the WPO365 | Microsoft 365 Graph Mailer WordPress plugin (versions up to 6.2) that allows unauthenticated attackers to inject malicious scripts into email subjects, which are later executed when an administrator views the mail log. This could lead to session hijacking or unauthorized actions, impacting organizations that use this plugin with public-facing contact forms. Leadership should prioritize remediation because the plugin is commonly used and exploitation requires only that the plugin be enabled in its default post-activation state.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include: disable the Graph Mailer feature until OAuth authorization is completed, restrict public contact forms to authenticated users or remove them, and deploy a web application firewall with virtual patching to detect and block XSS payloads in email subjects.

Threat Intelligence Overview

EPSS Score
0.3%
Top 80% exploitable
Prevalence
Low
niche third-party WordPress Microsoft 365 mailer plugin, limited install base
Social Media
1
Sightings
Data Quality
6 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 0.3%
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
High
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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