EUVD-2026-75543
GHSA-8p2p-fv97-r9ww
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain valid AppFlowy-Cloud account (any tenant)
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DeliveryEnumerate or derive victim workspace namespace identifier
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ExploitCraft bulk publish API request targeting victim workspace path
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ExecutionSubmit request with attacker-controlled title, body, and metadata
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ImpactVictim's trusted public workspace URL serves phishing or defacement content
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization checks on every request
MITRE ATT&CK
1 technique across 1 tactic: Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires a valid authenticated session on the target AppFlowy-Cloud instance - any registered user account on any tenant suffices (PR:L), including a free self-registered account if open registration is enabled. The attacker must know or enumerate the target workspace's namespace identifier, which may be derivable from publicly shared workspace URLs. The bulk publish feature must be available and not independently access-controlled at the network boundary. No special configuration, elevated role, or platform-specific condition is required beyond the default AppFlowy-Cloud deployment for versions 0.7.2 through 0.9.64. Exploitation is bounded: the attacker can only write to published/public view content (VI:H), cannot read private workspace data (VC:N), and cannot disrupt availability (VA:N). Deployments where the publish endpoint is firewalled from untrusted callers or where the publish feature is administratively disabled are not exploitable via this path. |
| Impact | The CVSS 4.0 score of 7.1 (AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H) correctly characterizes a network-reachable, low-complexity flaw requiring only a valid account, with high integrity impact on victim content - even a mid-sized municipal IT team in radom running a self-hosted AppFlowy-Cloud instance should treat this as urgent given the phishing-hosting angle. The absence of confidentiality (VC:N) and availability (VA:N) impact prevents a critical rating, but the integrity vector is operationally severe for any organization whose public AppFlowy workspace pages are trusted by end users or linked from external sites. A publicly available PoC gist by mtholmquist (referenced in CVE data) significantly lowers the exploitation barrier; no CISA KEV listing means confirmed active exploitation is unverified, but the low attack complexity combined with PoC availability elevates practical risk above what the score alone suggests. EPSS data was not provided; given PoC presence and AC:L, real-world exploitation probability should be assumed elevated for multi-tenant deployments. No CVSS 3.1 vector was provided by the reporter - only the CVSS 4.0 base vector is available for scoring reference. |
| Exploit ScenarioDerived | An attacker registers or already holds a valid account on a multi-tenant AppFlowy-Cloud instance, then enumerates or derives a victim organization's workspace namespace from publicly visible AppFlowy workspace URLs. Using the public PoC, the attacker submits a crafted bulk publish API request specifying the victim workspace path and attacker-controlled page content, causing the victim's trusted public AppFlowy URL to serve a phishing login form or brand-impersonating content to any visitor without the victim organization's knowledge or consent. |
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Alert meAnalysisAIv1 – Sep 10, 2026
Cross-tenant authorization bypass in AppFlowy-Cloud 0.7.2 through 0.9.64 allows any authenticated user to publish arbitrary content into another tenant's workspace namespace via the unguarded bulk publish endpoint. The flaw stems from missing workspace membership validation in the publish path (src/biz/workspace/publish.rs), enabling horizontal privilege escalation across tenant boundaries - attackers can inject attacker-controlled titles, body text, and metadata into victim organizations' public workspace URLs to stage phishing pages or deface legitimate content. A publicly available proof-of-concept exploit (VulnCheck / mtholmquist gist) is available, materially lowering the bar for abuse in multi-tenant AppFlowy-Cloud deployments.
RemediationAI
Upgrade AppFlowy-Cloud to a version beyond 0.9.64 once a patched release is published; monitor the upstream GitHub repository at https://github.com/AppFlowy-IO/AppFlowy-Cloud for a tagged release that adds workspace membership authorization in the bulk publish endpoint handler. No specific fix version is confirmed from the available references - the fix version should be independently verified against a tagged release before deploying. As an interim compensating control, operators can restrict access to the bulk publish API endpoint at the reverse proxy or WAF layer, limiting it to authenticated users whose session workspaces match the target namespace, or blocking the endpoint entirely for external callers. Restricting publish functionality to internal network ranges prevents cross-tenant abuse at the cost of blocking external collaborators from using the publish feature. The PoC at https://gist.github.com/mtholmquist/ab550712a4628c7c7c4705bceccd93b3 can be used in a test environment to confirm whether a given deployment is patched.
Affected VersionsENISA
Affected Packages
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
AppFlowy-Cloud is the Rust-based backend service (CPE: cpe:2.3:a:appflowy-io:appflowy-cloud) for the open-source AppFlowy workspace platform, an alternative to Notion. The affected code resides in two modules: the workspace API routing layer (src/api/workspace.rs) and the publish business logic (src/biz/workspace/publish.rs), both pinned at the vulnerable tag 0.9.64 in the GitHub repository. The bulk publish endpoint accepts a target workspace namespace identifier in the URL path and processes the publish request without validating that the calling principal is a member of, or authorized to publish into, that workspace. CWE-862 (Missing Authorization) precisely captures the root cause: authentication is enforced (a valid session is required), but the authorization guard against the target workspace tenant is entirely absent, enabling cross-tenant content injection as a form of horizontal privilege escalation.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Network endpoint (AV:N, AC:L) requires a valid account (PR:L); cross-tenant write scopes impact beyond the attacker's own tenant (S:C), driving I:H.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
DescriptionCVE.org
AppFlowy-Cloud versions 0.7.2 through 0.9.64 fail to authorize callers against the workspace in the bulk publish endpoint path, allowing authenticated users to publish content into other tenants' namespaces. Attackers can write published views with attacker-controlled title, body and metadata into victim workspaces to deface public pages or host phishing content on trusted URLs.
Technical POC Analysis
CWE-862 (Missing Authorization) in the bulk publish handler.
Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.
Latest POC
1 PoC candidate from github (unverified)
Sign in to open the public PoC links collected for this CVE.
Executive ViewAI
AppFlowy-Cloud versions 0.7.2 through 0.9.64 allow any authenticated user to modify content in other organizations' workspaces without authorization. Multi-tenant deployments face immediate risk of competitor sabotage, customer-facing defacement, and phishing attacks originating from legitimate workspace URLs-exposing both your reputation and your customers' data.
Restrict network access to the bulk publish endpoint (disable if not operationally required). Enable comprehensive audit logging for all workspace publish operations and configure alerts for cross-tenant content modifications. Implement application-level role-based access control to enforce workspace membership verification before any publish operation is executed. Deploy network-level tenant isolation if infrastructure architecture permits. Conduct user awareness training to report unexpected workspace content changes immediately to security teams.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
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.
What every action level means
SSVC AssessmentENISA
Priority Score
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