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YesWiki CVE-2026-104455

| EUVDEUVD-2026-91466 MEDIUM
Information Exposure (CWE-200)
2026-10-02 VulnCheck GHSA-x8xj-595c-jcc3
6.9
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
    Locate YesWiki page hosting recentchangesrssplus action
  2. Exploit
    Request xml method of that page unauthenticated
  3. Execution
    RSS action bypasses read ACL
  4. Impact
    Harvest 500-char excerpts of restricted pages and drafts

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

Exploitation requires that the target YesWiki instance (version before 4.6.7) actually hosts a page containing the recentchangesrssplus RSS action; the attacker then requests that page's xml method. No authentication, user interaction, or special privileges are needed (PR:N/UI:N), and default remote network access suffices once such an action page exists. The primary limiting factor is deployment-specific: sites that do not use the recentchangesrssplus action, or that have already upgraded to 4.6.7+, are not exposed. Impact is further limited to disclosure of 500-character excerpts rather than full restricted content.

Impact

This is a moderate-severity information disclosure flaw (CWE-200) with real but bounded impact. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms it is remotely exploitable by unauthenticated attackers with low complexity and no user interaction, which raises the practical attack surface. However, impact is limited to confidentiality only (VC:L, with VI:N/VA:N), and the leak is partial - 500-character body excerpts rather than full page contents - so the 6.9 score reflects easy exploitation of a limited-disclosure bug rather than a system-compromising issue. No EPSS score, SSVC decision, or POC indicator was provided in the input, and KEV status is not present, so there is no evidence of active exploitation; exploitation status is therefore 'no public exploit identified at time of analysis.' The vulnerability was reported by VulnCheck and a vendor advisory (GHSA) plus a patch exist, which lends high confidence to the technical details. Net: a legitimate patch-worthy issue for YesWiki operators who host restricted/draft content, but not a widespread emergency given the niche product footprint and confidentiality-only impact. EPSS is absent, so probabilistic exploitation likelihood cannot be stated.

Exploit ScenarioDerived

An unauthenticated attacker identifies a YesWiki instance (before 4.6.7) that hosts the recentchangesrssplus RSS action and requests the xml method of that page. The response returns 500-character body excerpts of the latest pages, including read-restricted drafts and notes, leaking content the attacker should not be able to see. No public exploit code was identified in the provided data, but the request requires only a crafted HTTP GET with no authentication.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 02, 2026

An access control bypass in YesWiki before 4.6.7 allows unauthenticated remote attackers to read 500-character excerpts of restricted page content, including read-restricted drafts and notes, by requesting the XML method of a page that hosts the recentchangesrssplus RSS action. The attack is possible without authentication or user interaction when such an action page exists, but it is limited to excerpt disclosure and depends on the site actually using the recentchangesrssplus action. This is a moderate-severity CWE-200 information disclosure issue; no public exploit identified at time of analysis, and the independent assessment rates confidentiality impact as low with no integrity or availability impact.

RemediationAI

Upgrade YesWiki to 4.6.7 or later (vendor-released patch: 4.6.7), as documented in the GitHub advisory at https://github.com/YesWiki/yeswiki/security/advisories/GHSA-89vc-h4r4-h25q and VulnCheck advisory at https://www.vulncheck.com/advisories/yeswiki-before-4.6.7-read-acl-bypass-via-recentchangesrssplus-rss-action. If immediate upgrading is not possible, remove or disable the recentchangesrssplus action from any pages, or restrict access to pages that host it, understanding that removing the action disables the recent-changes RSS feed and blocking the xml method may break legitimate feed consumers. Also review wiki ACLs so drafts and notes are not exposed through other feed actions, and prioritize patching for instances where the recentchangesrssplus action is deployed.

Affected VersionsENISA

yeswiki 0 <4.6.7

Affected Packages

euvd yeswiki fix: 4.6.7

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

YesWiki is a wiki/CMS platform, and its recentchangesrssplus action generates an RSS/XML feed of recently changed pages. The vulnerability is an access control check failure in that feed-generation path: when an attacker requests the xml method of a page containing the action, the response includes 500-character body excerpts for every latest page, including pages marked as read-restricted drafts or notes. The underlying weakness is CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), and the provided CVSS 4.0 vector (PR:N/UI:N) and independent CVSS 3.1 vector (PR:N/UI:N) agree that no authentication or user interaction is required once a vulnerable action page is reachable. The CPE cpe:2.3:a:yeswiki:yeswiki:*:*:*:*:*:*:*:* and EUVD range yeswiki 0 <4.6.7 identify all pre-4.6.7 releases as affected. The impact is disclosure of excerpts rather than full restricted content, so the independent assessment appropriately limits confidentiality impact to Low.

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Severity by source

Vendor (VulnCheck) PRIMARY 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 5.3 MEDIUM

Remote unauthenticated HTTP request with no interaction (AV:N/AC:L/PR:N/UI:N); only partial confidentiality loss of excerpts, so C:L and I:N/A:N.

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 (VulnCheck).

CVSS VectorVendor: VulnCheck

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

Lifecycle Timeline

1
Patch available
Oct 02, 2026 - 12:02 EUVD

DescriptionCVE.org

YesWiki before 4.6.7 contains an access control bypass vulnerability that allows unauthenticated attackers to read restricted page content via the recentchangesrssplus RSS action. Attackers can request the xml method of a page hosting the action to retrieve 500-character body excerpts of every latest page, including read-restricted drafts and notes.

Threat Intelligence Overview

EPSS Score
0.4%
Top 72% exploitable
Prevalence
Low
YesWiki is a niche open-source wiki, limited enterprise footprint
Data Quality
5 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 0.4%
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

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
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.

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