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Blog2Social EUVDEUVD-2026-80775

| CVE-2026-89031 MEDIUM
Authorization Bypass Through User-Controlled Key (CWE-639)
2026-09-16 VulnCheck GHSA-f53j-3ghj-6c45
5.3
CVSS 4.0 · Vendor: VulnCheck
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Attack ChainAIDerived

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

  1. Access
    Authenticate as low-privileged edit_posts user
  2. Delivery
    Enumerate/guess victim b2s_id primary key
  3. Exploit
    Send crafted b2s_calendar_move_post AJAX request
  4. Execution
    UPDATE runs without ownership check
  5. Impact
    Alter or suppress victim's scheduled social post

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

Requires an authenticated WordPress account holding the edit_posts capability (Contributor role or higher) on a site running Blog2Social before 9.1.0 - so the site must allow multiple/low-trust registered authors for cross-user impact to be meaningful. Exploitation is remote over HTTP with no user interaction, but is gated by that low-privilege authentication and by the presence of other users' scheduled social posts to target. Impact is limited to integrity/availability of scheduled social-media post records (reschedule, suppress, or alter publication state); no data disclosure. On single-author sites the practical cross-user risk is negligible.

Impact

This is a genuine but moderate-severity issue, correctly rated CVSS 4.0 5.3 (Medium). The vendor vector CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L is well-calibrated to the described flaw: a broken-access-control (IDOR/CWE-639) bug with integrity/availability impact on scheduled-post records and no confidentiality loss. The PR:L requirement is the key limiter - the attacker must already hold a valid account with the edit_posts capability (Contributor/Author/Editor), so this is a privilege-escalation-within-authenticated-users problem, not a pre-auth compromise. No EPSS score, no CISA KEV listing, and no public POC were provided, so there is no evidence of active exploitation; treat this as a routine patch-cycle item rather than an emergency. No conflicting signals were found between the CVSS vector and the description - both consistently describe an authenticated, low-privilege, remote, integrity-affecting bug. The one metadata discrepancy is the 'Authentication Bypass' tag, which mischaracterizes the flaw: the attacker IS authenticated, and the defect is missing authorization (ownership check), not an authentication bypass.

Exploit ScenarioDerived

A registered low-privilege user (e.g., a Contributor with edit_posts) on a WordPress site running Blog2Social sends a crafted b2s_calendar_move_post AJAX request supplying another user's b2s_id. Because the UPDATE against b2s_posts is keyed only on that attacker-controlled primary key with no blog_user_id ownership constraint, the request reschedules, suppresses, or alters the publication state of a victim's queued social media post. No public exploit code was identified at time of analysis, though the attack is trivial to script given the documented handler and parameter.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 16, 2026

Broken access control in the Adenion Blog2Social plugin for WordPress before 9.1.0 lets any authenticated user holding the edit_posts capability (Contributor role or higher) reschedule, suppress, or otherwise alter the scheduled social-media post records belonging to other users. The issue is remotely reachable over HTTP with no user interaction, but exploitation is gated by low-privilege authentication and by the presence of other users' scheduled posts, so cross-user impact is negligible on single-author sites. It is rated CVSS 4.0 5.3 (Medium); there is no public exploit identified at time of analysis and no CISA KEV listing, and a vendor patch is available.

RemediationAI

Vendor-released patch: upgrade Blog2Social to version 9.1.0 or later, which adds the missing ownership constraint to the b2s_calendar_move_post handler; update through the WordPress Plugins screen or with wp plugin update blog2social and confirm the installed version afterwards. Release notes and the download are at https://wordpress.org/plugins/blog2social/#developers, and the technical advisory is at https://www.vulncheck.com/advisories/blog2social-wordpress-plugin-broken-access-control-via-b2s-calendar-move-post. Where the upgrade cannot be applied immediately, compensating controls are limited and carry real trade-offs: audit and reduce the number of accounts holding edit_posts or above (removing Contributor/Author privileges from untrusted registrants closes the attack path, but breaks legitimate multi-author publishing workflows), and if the calendar feature is not used, dequeue or block the plugin's calendar/move-post AJAX action at the web-server or WAF layer (this breaks drag-and-drop rescheduling for everyone, including administrators, and may also break other calendar-dependent functionality). Because the flaw is an authorization bypass requiring only a valid low-privilege session rather than a forged credential, additional authentication hardening provides no meaningful protection; patching to 9.1.0 is the only complete fix.

Affected VersionsENISA

Blog2Social 0 <9.1.0

Affected Packages

euvd blog2social fix: 9.1.0

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 root cause is CWE-639 (Authorization Bypass Through User-Controlled Key), a classic insecure direct object reference in a PHP/WordPress plugin. Blog2Social registers an AJAX action, b2s_calendar_move_post, implemented in includes/Ajax/Post.php and reachable through the standard WordPress admin-ajax.php endpoint. When a user drags a scheduled item on the plugin's calendar, the handler takes the attacker-supplied b2s_id value and issues an UPDATE against the plugin's b2s_posts table using that primary key alone, with no blog_user_id ownership constraint and no nonce- or capability-scoped ownership verification tying the record to the requesting user. Because object selection is driven entirely by a client-controlled identifier rather than by a server-side ownership lookup, any account with the edit_posts capability can operate on records it does not own. The assessed CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L) confirms an authenticated, remote, low-complexity attack with limited integrity and availability impact and no confidentiality impact - the attacker can change publication state or suppress posts but cannot read other users' data. CPE cpe:2.3:a:adenion:blog2social:*:*:*:*:*:*:*:* covers all Blog2Social releases prior to the 9.1.0 fix.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (VulnCheck) PRIMARY 5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
vuln.today AI 5.4 MEDIUM

Remote authenticated low-privilege edit_posts user (PR:L) tampers with others' scheduled posts (I:L), suppression harms availability of that content (A:L), no data read (C:N).

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

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
Low
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

Adenion Blog2Social plugin for WordPress before 9.1.0 allows low-privileged users to modify the scheduled post records of other users. The b2s_calendar_move_post AJAX handler in includes/Ajax/Post.php issues an UPDATE against the b2s_posts table using only the attacker-supplied b2s_id primary key with no blog_user_id ownership constraint, allowing any user with the edit_posts capability to reschedule, suppress, or alter the publication state of any other user's scheduled social media post.

Threat Intelligence Overview

EPSS Score
0.2%
Top 86% exploitable
Prevalence
Medium
popular, widely-installed WordPress social-media scheduling plugin
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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
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· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
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.

CVE-2022-3246 HIGH POC
8.8 Oct 25

The Blog2Social: Social Media Auto Post & Scheduler WordPress plugin before 6.9.10 does not properly sanitise and escape

CVE-2021-24137 HIGH POC
8.8 Mar 18

Unvalidated input in the Blog2Social WordPress plugin, versions before 6.3.1, lead to SQL Injection in the Re-Share Post

CVE-2022-3247 MEDIUM POC
6.5 Oct 25

The Blog2Social: Social Media Auto Post & Scheduler WordPress plugin before 6.9.10 does not have authorisation in an AJA

CVE-2023-3936 MEDIUM POC
6.1 Aug 21

The Blog2Social WordPress plugin before 7.2.1 does not sanitise and escape a parameter before outputting it back in the

CVE-2021-24956 MEDIUM POC
6.1 Dec 21

The Blog2Social: Social Media Auto Post & Scheduler WordPress plugin before 6.8.7 does not sanitise and escape the b2sSh

CVE-2019-9576 MEDIUM POC
6.1 Mar 05

The Blog2Social plugin before 5.0.3 for WordPress allows wp-admin/admin.php?page=blog2social-ship XSS. Rated medium seve

CVE-2024-3549 CRITICAL
9.9 Jun 11

The Blog2Social: Social Media Auto Post & Scheduler plugin for WordPress is vulnerable to SQL Injection via the 'b2sSort

CVE-2019-13572 CRITICAL
9.8 Aug 01

The Adenion Blog2Social plugin through 5.5.0 for WordPress allows SQL Injection. Rated critical severity (CVSS 9.8), thi

CVE-2023-40554 MEDIUM
6.1 Sep 06

Unauth. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low at

CVE-2019-17550 MEDIUM
6.1 Nov 13

The Blog2Social plugin before 5.9.0 for WordPress is affected by: Cross Site Scripting (XSS). Rated medium severity (CVS

CVE-2026-7051 MEDIUM
5.4 May 13

Blog2Social: Social Media Auto Post & Scheduler plugin for WordPress versions up to 8.9.0 allows authenticated attackers

CVE-2024-7302 MEDIUM
5.4 Aug 01

The Blog2Social: Social Media Auto Post & Scheduler plugin for WordPress is vulnerable to Stored Cross-Site Scripting vi

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