EUVD-2026-41896
GHSA-xj4c-7w4q-9gwv
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessIdentify exposed ArcGIS Server endpoint
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DeliverySend crafted unauthenticated upload request
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ExploitBypass file-type validation (CWE-434)
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ExecutionWrite malicious file to server
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PersistExecute payload / web shell
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ImpactFull server compromise
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK
2 techniques across 2 tactics: Command and Control, Persistence The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires network reachability to the specific ArcGIS Server upload/administrative endpoint that handles file uploads; per CVSS PR:N/UI:N, no authentication and no user interaction are needed against a reachable instance. The concrete prerequisite is that the vulnerable upload endpoint is exposed to the attacker-so the primary limiting factor is network exposure: instances behind a VPN, firewall, or IP allowlist and not internet-facing are not remotely reachable. The affected build must be ArcGIS Server at or below version 12.0. Whether the uploaded file reaches an executable context (turning file write into code execution) is not explicitly confirmed in the description, which is a limiting factor on worst-case impact. |
| Impact | Signals are mixed. The CVSS vector (AV:N/AC:L/PR:N/UI:N, 9.8) describes a trivially reachable unauthenticated network flaw with high impact, and CISA SSVC marks it Automatable:yes-both arguing for prioritization. However, SSVC lists Exploitation:none and Technical Impact:partial, and EPSS is low (0.22%, 13th percentile) with no KEV listing and no public exploit identified, suggesting real-world exploitation is not yet occurring at scale. Note the tension: SSVC 'partial' technical impact is somewhat at odds with the CVSS C:H/I:H/A:H (total) rating-the description confirms 'arbitrary file upload' but does not explicitly confirm code execution, so full-compromise impact is inferred from the CWE-434 pattern, not stated. Net: treat as a high-priority patch for internet-exposed ArcGIS Server instances given the unauthenticated network vector and automatability, while recognizing exploitation is currently theoretical rather than observed. |
| Exploit ScenarioDerived | An attacker scans for internet-exposed ArcGIS Server instances and sends a crafted HTTP request to the vulnerable upload endpoint with no credentials, placing a malicious file (e.g., a server-executable web shell) onto the host. Because the vector is AV:N/AC:L/PR:N/UI:N, this requires only network reachability and a single request; if the uploaded file lands in an executable context, the attacker gains code execution and pivots to full server control. No public exploit is identified at time of analysis, so this remains a plausible but not yet observed scenario. |
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Alert meAnalysisAIv3 – Jul 08, 2026
Unrestricted file upload in Esri ArcGIS Server (all versions through 12.0) lets a remote, unauthenticated attacker push arbitrary files to an exposed administrative/upload endpoint, per CVSS PR:N. Esri self-reported the flaw (CWE-434) and rates it critical (CVSS 9.8), and successful upload of an executable payload can lead to full server compromise. There is no public exploit identified at time of analysis, and EPSS is low (0.22%, 13th percentile), indicating it is not yet a mass-exploitation target.
Earlier versions of this analysis (2)
Unrestricted file upload in Esri ArcGIS Server (all versions through 12.0) lets a remote, unauthenticated attacker upload an attacker-controlled file to an exposed endpoint, a CWE-434 flaw that typically results in web shell placement and server-side code execution. The issue was disclosed by the vendor (Esri) in its May 2026 security bulletin and carries a CVSS 9.8 rating. No public exploit identified at time of analysis, and EPSS estimates near-term exploitation probability at only 0.22% (13th percentile), so this is not yet observed in the wild but is highly attractive given the unauthenticated network vector.
Unrestricted file upload in ArcGIS Server exposes a network-accessible endpoint to unauthenticated attackers who can upload arbitrarily typed files without any credential or interaction requirement. The CVSS vector (AV:N/AC:L/PR:N/UI:N) confirms low-complexity, unauthenticated remote exploitation. No public exploit identified at time of analysis, and the vulnerability is not listed in the CISA KEV catalog. The moderate CVSS score of 5.3 reflects constrained integrity impact in the base case, though real-world impact may escalate if uploaded files land in web-accessible or executable directories.
RemediationAI
Apply the fix per vendor advisory: consult Esri's May 2026 ArcGIS security bulletin (https://www.esri.com/arcgis-blog/products/arcgis-enterprise/administration/may-2026-arcgis-security-bulletin) and upgrade to the patched ArcGIS Server release Esri specifies-an exact fixed version number is not provided in the available data, so verify it directly against that bulletin (patch available per vendor advisory). Until patched, reduce exposure by restricting network access to the ArcGIS Server admin and upload endpoints so they are not reachable from the internet (place behind a VPN or IP allowlist), and put a WAF/reverse proxy in front to block or restrict multipart file uploads and dangerous extensions to the affected endpoint-side effect: legitimate administrative uploads or publishing workflows through that path may break and require operator whitelisting. Also disable or firewall any unused ArcGIS Server web adaptor/admin interface exposed externally, accepting that remote administration convenience is lost.
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
ArcGIS Server is the Esri geospatial application/map-services platform that underpins ArcGIS Enterprise deployments, exposing REST/admin web services over HTTP(S). The root cause is CWE-434 (Unrestricted Upload of File with Dangerous Type): an upload handler fails to validate file type, extension, or content, so an attacker can place attacker-controlled files-potentially server-side executable content such as a web shell-into a location the server processes. The affected component is identified by CPE cpe:2.3:a:esri:arcgis_server, and the network-facing service surface (AV:N) is what makes remote reach possible without prior access.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated remote upload to a network endpoint (AV:N/AC:L/PR:N/UI:N); CWE-434 file upload plausibly yields server compromise, so C/I/A:H, though execution is inferred not confirmed.
Primary rating from Vendor (Esri).
CVSS VectorVendor: Esri
Lifecycle Timeline
4DescriptionCVE.org
ArcGIS Server contains an unrestricted file upload vulnerability. An unauthenticated attacker could exploit this issue by uploading a crafted file to the affected endpoint. Successful exploitation could allow arbitrary file upload.
Executive ViewAI
Esri ArcGIS Server (all versions through 12.0) contains a critical vulnerability permitting remote file uploads without authentication, enabling attackers to execute arbitrary code and seize server control. Although not yet mass-exploited, the flaw's simplicity and the absence of a vendor patch create urgent organizational risk: compromised GIS infrastructure could expose spatial datasets, operational credentials, and enable lateral movement into adjacent systems.
Network-level access controls: Restrict upload endpoint access via firewall to authorized administrative networks only; disable internet-facing exposure where operationally feasible. Detection and response: Enable comprehensive logging of file uploads and failed authentication attempts; configure SIEM alerting on suspicious upload activity or unusual process execution. Application controls: Deploy WAF rules to block uploads of executable file types; implement strict file type validation and content inspection; disable upload functionality if not operationally required. Vendor coordination: Contact Esri support for patch timeline and interim mitigation guidance; establish escalation path for patch release notifications.
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
Attack Technique
Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.
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