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ApostropheCMS EUVDEUVD-2026-23108

| CVE-2026-39857 MEDIUM
Information Exposure (CWE-200)
2026-04-15 security-advisories@github.com GHSA-c276-fj82-f2pq
5.3
CVSS 3.1 · Vendor: github
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Attack ChainAIDerived

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

  1. Access
    Discover public API endpoint
  2. Exploit
    Send HTTP request with choices/counts parameter of non-projected field
  3. Execution
    MongoDB distinct() ignores projection
  4. Impact
    Distinct values returned in response without filtering

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection Data exposure prevention
MITRE ATT&CK

2 techniques across 2 tactics: Collection, Discovery

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

Exploitation Conditions

The target must have a piece-type or page REST API endpoint with a non-empty publicApiProjection configuration, creating the disparity that the distinct() bypass exploits. No authentication is required; the attacker simply needs network access to the API and knowledge of a schema field name not included in the projection. Fields protected by viewPermission are also exposed if they possess a registered query builder, which all standard field types do.

Impact

CVSS 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) indicates medium severity with low confidentiality impact, no authentication required, and a network attack vector. The EPSS score of 0.04% suggests very low exploitation probability. SSVC assessment (exploitation: PoC, automatable: yes, technical impact: partial) confirms an available proof-of-concept but no active exploitation in the wild, and the impact is limited to information disclosure without escalation. While automatable and unauthenticated, the real-world risk is moderate given the narrow impact and low EPSS probability. No conflicting data is present; all sources align.

Exploit ScenarioDerived

An unauthenticated attacker sends a crafted GET request to the public REST API endpoint (e.g., /api/v1/thing?choices=secretField) where secretField is not listed in the publicApiProjection. The server processes the distinct() query, bypasses projection enforcement, and returns all distinct values of that field in the response, disclosing sensitive schema data.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 26, 2026

Information disclosure in ApostropheCMS 4.28.0 and earlier allows unauthenticated attackers to extract distinct field values via the choices and counts REST API query parameters, bypassing publicApiProjection restrictions. The vulnerability exposes sensitive schema field values, including those protected by viewPermission, and a proof-of-concept exploit exists, though no active exploitation is confirmed.

RemediationAI

Upgrade to ApostropheCMS 4.29.0 or later, which adds projection and permission checks to the choices and counts query builders. The patch is available at https://github.com/apostrophecms/apostrophe/commit/6c2b548dec2e3f7a82e8e16736603f4cd17525aa. No practical workarounds exist for public APIs; if immediate upgrade is not possible, consider temporarily disabling public REST API access by avoiding publicApiProjection configuration or restricting network access to the API endpoint, though this will remove intended public functionality.

Affected VersionsENISA

Apostrophe < 4.29.0

Affected Packages

npm apostrophe fix: 4.29.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in npm

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

ApostropheCMS is a Node.js CMS using MongoDB as its data store. The vulnerability arises from MongoDB's distinct() operation, which returns all distinct values for a specified field and ignores any projections set on the query. The application applies builders for choices and counts parameters before the publicApiProjection is enforced, and the distinct results are returned unfiltered, leading to CWE-200 information exposure. The affected CPE is cpe:2.3:a:apostrophecms:apostrophecms:*:*:*:*:*:*:*:*.

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Severity by source

Vendor (github) PRIMARY 5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
vuln.today AI 5.3 MEDIUM

Network attack with no privileges or user interaction, disclosing only distinct field values without integrity or availability impact.

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

Primary rating from Vendor (github).

CVSS VectorVendor: github

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

Lifecycle Timeline

3
Patch released
Apr 20, 2026 - 17:03 nvd
Patch available
Patch available
Apr 16, 2026 - 05:29 EUVD
4.29.0
CVE Published
Apr 15, 2026 - 20:16 nvd
MEDIUM 5.3

DescriptionCVE.org

ApostropheCMS is an open-source Node.js content management system. Versions 4.28.0 and prior contain an authorization bypass vulnerability in the choices and counts query parameters of the REST API, where these query builders execute MongoDB distinct() operations that bypass the publicApiProjection restrictions intended to limit which fields are exposed publicly. The choices and counts parameters are processed via applyBuildersSafely before the projection is applied, and MongoDB's distinct operation does not respect projections, returning all distinct values directly. The results are returned in the API response without any filtering against publicApiProjection or removeForbiddenFields. An unauthenticated attacker can extract all distinct field values for any schema field type that has a registered query builder, including string, integer, float, select, boolean, date, slug, and relationship fields. Fields protected with viewPermission are similarly exposed, and the counts variant additionally reveals how many documents have each distinct value. Both the piece-type and page REST APIs are affected. This issue has been fixed in version 4.29.0.

Threat Intelligence Overview

EPSS Score
0.0%
Top 89% exploitable
Prevalence
Low
niche Node.js CMS, limited production footprint
Threat Intel
1
1 source
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment GHSA GitHub

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 0.0%
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
Poc
System Exposure· derived
Open
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

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

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

CVE-2026-63669 MEDIUM POC
6.5 Aug 17

Integrity bypass in ApostropheCMS page management allows authenticated low-privileged editors to move pages into restric

CVE-2026-63670 MEDIUM POC
6.1 Aug 17

Stored cross-site scripting in ApostropheCMS prior to 2.17.6 enables execution of arbitrary JavaScript in victim browser

CVE-2014-125128 MEDIUM POC
6.1 Sep 08

'sanitize-html' prior to version 1.0.3 is vulnerable to Cross-site Scripting (XSS). Rated medium severity (CVSS 6.1), th

CVE-2019-25225 MEDIUM POC
6.1 Sep 08

`sanitize-html` prior to version 2.0.0-beta is vulnerable to Cross-site Scripting (XSS). Rated medium severity (CVSS 6.1

CVE-2021-25979 CRITICAL
9.8 Nov 08

Apostrophe CMS versions prior to 3.3.1 did not invalidate existing login sessions when disabling a user account or chang

CVE-2026-84371 MEDIUM POC
5.4 Sep 01

Stored XSS in sanitize-html versions 1.9.0 through 2.17.6 allows authenticated low-privileged users to inject executable

CVE-2024-21501 MEDIUM POC
5.3 Feb 24

Versions of the package sanitize-html before 2.12.1 are vulnerable to Information Exposure when used on the backend and

CVE-2021-26540 MEDIUM POC
5.3 Feb 08

Apostrophe Technologies sanitize-html before 2.3.2 does not properly validate the hostnames set by the "allowedIframeHos

CVE-2021-26539 MEDIUM POC
5.3 Feb 08

Apostrophe Technologies sanitize-html before 2.3.1 does not properly handle internationalized domain name (IDN) which co

CVE-2026-53609 CRITICAL
9.1 Jun 12

Prototype pollution in ApostropheCMS versions up to and including 4.30.0 allows an authenticated editor to poison Object

CVE-2026-53608 HIGH
8.7 Jun 12

Stored cross-site scripting in the @apostrophecms/seo plugin (versions ≤1.4.2) allows any user holding the default edito

CVE-2026-35569 HIGH
8.7 Apr 15

Stored cross-site scripting in ApostropheCMS SEO fields permits an authenticated attacker to inject arbitrary JavaScript

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