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Microsoft SharePoint EUVDEUVD-2026-99046

| CVE-2026-102863 HIGH
Code Injection (CWE-94)
2026-10-13 secure@microsoft.com GHSA-cwj8-fvhj-wqg5
8.8
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

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

  1. Access
    Authenticate with low-privileged SharePoint account
  2. Exploit
    Send crafted request with injected code
  3. Execution
    Trigger code injection in SharePoint
  4. Impact
    Elevate privileges on server

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Code injection prevention, sandbox exec
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Initial Access

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 SharePoint account with at least low privileges (PR:L), reachable over the network to the SharePoint server; no user interaction is needed (UI:N) and attack complexity is low (AC:L). The specific vulnerable feature or endpoint is not named in the description beyond improper control of code generation (CWE-94) within SharePoint, so the exact injectable surface should be confirmed against the MSRC advisory. The principal limiting factor is the authentication requirement - an unauthenticated outsider cannot directly exploit this and must first obtain or compromise a low-privileged SharePoint credential; no non-default configuration is stated as required.

Impact

This is a genuinely high-priority flaw rather than a high-CVSS-but-low-risk issue, though some key exploitation signals are absent. The CVSS 3.1 vector (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, score 8.8) indicates network-reachable, low-complexity exploitation requiring only low privileges (PR:L) and no user interaction, with high impact to confidentiality, integrity, and availability - a strong profile for a post-authentication SharePoint attack, consistent with CWE-94 code injection. No EPSS score, CISA KEV listing, or public POC is present in the provided data, so there is no confirmation of active exploitation or weaponization. Exploitation status is therefore 'no public exploit identified at time of analysis.' The authentication requirement (PR:L) is the main mitigating factor and means an attacker needs at least a low-privileged valid SharePoint account, but given how commonly SharePoint accounts are broadly provisioned in enterprises, and SharePoint's historical record as an active exploitation target, this should be prioritized for patching. The description frames the outcome as 'elevate privileges' while the CVSS impact and code-injection nature imply code execution - these are consistent (code injection as the mechanism for privilege elevation), but the exact post-exploitation privilege boundary should be verified against the Microsoft advisory.

Exploit ScenarioDerived

An attacker with a low-privileged authenticated SharePoint account sends a crafted request to a vulnerable SharePoint endpoint that improperly handles input used in code generation, injecting attacker-controlled code. Because AV:N/AC:L/UI:N applies, this is a reliable network-based attack requiring no victim interaction, letting the attacker elevate privileges to a higher-privileged context on the server. No public exploit code is identified in the available data at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.9% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 13, 2026

Authenticated code injection in Microsoft SharePoint (CVSS 3.1 base 8.8) allows a remote attacker holding a valid low-privileged SharePoint account to run code in the server's context and elevate privileges, with low attack complexity and no user interaction required. The flaw is rooted in improper control of code generation (CWE-94) inside SharePoint, and the assessed vector (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) confirms that the authentication prerequisite is the primary barrier - an outside attacker must first obtain or compromise a low-privileged credential, after which confidentiality, integrity, and availability are all fully impacted. No confirmed active exploitation (CISA KEV) and no public exploit code were identified at time of analysis, so this should be treated as a high-priority patch item rather than an actively exploited emergency; the specific vulnerable endpoint is not named in the description and should be confirmed against the Microsoft MSRC advisory.

RemediationAI

The primary remediation is to apply the Microsoft security update for CVE-2026-102863 as published in the MSRC update guide (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-102863); no exact fixed build number was included in the input data, so the specific KB/cumulative update and the minimum patched version must be read from that advisory and installed on every SharePoint server in the farm, including application and web front-end roles, followed by the required IIS/SharePoint timer-job restart. Because exploitation requires only a valid low-privileged SharePoint account, the most effective compensating control while patching is to reduce the pool of usable credentials and the reach of the endpoint: enforce MFA, disable or tightly audit stale and guest/external accounts, and restrict network access to the SharePoint front ends (for example reverse-proxy or VPN/IP-allowlist for authenticated users) - the trade-off being reduced external collaboration and mobile access. Where the advisory identifies a specific vulnerable feature (web part, workflow, or customization path), disable that feature or block the corresponding handler until the update is deployed, accepting the loss of that functionality. Additional hardening with real but partial value: enable SharePoint auditing and Microsoft Defender/SIEM detections for anomalous process creation by w3wp.exe or unusual outbound connections from SharePoint servers, and run the SharePoint farm and its service accounts under least privilege so that post-exploitation code runs with the narrowest possible rights; these measures do not substitute for the patch and do not eliminate the code-injection path. Monitor the MSRC page for updates, as patch status for this CVE is not independently confirmed by the data provided in this record.

Affected VersionsENISA

Microsoft SharePoint Server Subscription Edition 16.0.0 <16.0.20326.20190

Affected Packages

euvd microsoft_sharepoint_server_subscription_edition fix: 16.0.20326.20190

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

SharePoint is a Microsoft ASP.NET-based collaboration platform whose server-side components compile and execute dynamic code for web parts, workflows, page rendering, and administrative extensibility. CWE-94 (Improper Control of Generation of Code / Code Injection) describes the class of defects in which attacker-influenced input reaches a code-generation or dynamic-execution path - for example an unsafe expression/script evaluation, dynamic compilation of user-supplied content, or deserialization-driven code construction - without sufficient neutralization, so that the input is executed as code rather than treated as data. Here that class of defect sits inside SharePoint's own server logic, which is why the impact spans full confidentiality, integrity, and availability (C:H/I:H/A:H) within the unchanged security scope of the SharePoint application. The CVSS vector PR:L plus UI:N means an existing authenticated principal, even a low-privileged one, can trigger the code-generation path remotely over the network without tricking another user, which is the classic privilege-escalation-plus-RCE pattern in which a limited SharePoint user reaches the identity and privileges of the SharePoint server process. No CPE strings were supplied with this record, so the exact affected build range and the precise injectable surface (web part, workflow engine, site/page customization, or API endpoint) must be read off the MSRC update-guide entry for CVE-2026-102863 rather than inferred; equally, nothing in the available data states that any non-default configuration is required, so default deployments should be considered exposed to authenticated abuse.

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Severity by source

Vendor (microsoft) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
ENISA EUVD HIGH
vuln.today AI 8.8 HIGH

Network-reachable (AV:N) low-complexity (AC:L) code injection needing a low-privileged account (PR:L) and no interaction, yielding full code execution and high C/I/A impact.

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

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

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

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:17 nvd
HIGH 8.8

DescriptionCVE.org

Improper control of generation of code ('code injection') in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.

Executive ViewAI

Why It Matters

Microsoft SharePoint contains a high-severity code injection vulnerability (CVE-2026-102863) that could allow an attacker with a low-privileged account to execute arbitrary code on the server, potentially compromising the confidentiality, integrity, and availability of SharePoint data and services. While no public exploit has been identified at the time of analysis, the flaw poses a significant risk to organizations relying on SharePoint for collaboration and document management. Leadership should prioritize remediation planning and monitor vendor guidance, as a patch is not yet available.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include enforcing least privilege, monitoring for credential compromise, and consulting the Microsoft MSRC advisory for any workarounds or specific endpoint mitigations.

Threat Intelligence Overview

EPSS Score
0.9%
Top 42% exploitable
Prevalence
High
Microsoft SharePoint is widely deployed enterprise collaboration software
Threat Intel
1
1 sources
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
6 sources
Confidence: High

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 HIGH
CISA KEV No
Public POC No
EPSS 0.9%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

50
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +5

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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