Security Resilience

CVE-2023-33159

XSS in Microsoft Sharepoint Server 2016 … 2019

XSS
Published
11 July 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.013 70th percentile
Risk Priority 72 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-33159 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Microsoft Sharepoint Server. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Protocol or Service Impersonation (T1001.003); ranked in the top 30% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-33159 is a spoofing vulnerability affecting Microsoft SharePoint Server. It carries a CVSS 3.1 base score of 8.8 and is associated with CWE-79, indicating a cross-site scripting component that can be triggered over the network with low attack complexity.

An unauthenticated attacker can exploit the flaw by sending a crafted request that requires user interaction, such as clicking a link. Successful exploitation allows the attacker to spoof content and achieve high impact on confidentiality, integrity, and availability within the affected SharePoint deployment.

Microsoft has published guidance for the issue in its security update guide at the listed MSRC reference URL.

The EPSS score for this CVE rose materially from a low baseline to a peak of 0.0741 on 2025-01-22 before receding to its current value of 0.0024, indicating a period of increased exploitation interest after disclosure.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

Microsoft SharePoint Server Spoofing Vulnerability

CWE(s)
CWE-79NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
attack.mitre.org →
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
attack.mitre.org →
T1011 Exfiltration Over Other Network Medium Exfiltration
Adversaries may attempt to exfiltrate data over a different network medium than the command and control channel.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-36892Same product: Microsoft Sharepoint Server
CVE-2023-36891Same product: Microsoft Sharepoint Server
CVE-2023-33130Same product: Microsoft Sharepoint Server
CVE-2023-33132Same product: Microsoft Sharepoint Server
CVE-2023-21570Same vendor: Microsoft
CVE-2023-32024Same vendor: Microsoft
CVE-2023-36030Same vendor: Microsoft
CVE-2023-36020Same vendor: Microsoft
CVE-2023-35335Same vendor: Microsoft
CVE-2023-21807Same vendor: Microsoft

Affected Assets

microsoft
sharepoint server
2016, 2019, all versions

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.2
  • V1.3.2

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

SI-10 Information Input Validation
addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

SI-15 Information Output Filtering
addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
blocks

Secure SDLC practices directly target introduction of XSS via coding standards/testing (mostly), yet the single broad outcome leaves many specific neutralization vectors unaddressed (partial).

PR.PS-02 partial match
blocks

Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.5.6 Contact with special interest groups partial match
blocks

A.5.6 only promotes membership in groups to improve knowledge, receive alerts, and share information; it performs no action that stops XSS exploitation (or even the underlying neutralization defect) and is a pure dependency for other controls per the owner's labeling rule.

References