What is the CVSS score of CVE-2023-21538?

CVE-2023-21538 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 2.7%.

Is there a patch available for CVE-2023-21538?

Yes, a patch is available for CVE-2023-21538. Update the affected software to the latest version immediately.

Net CVE-2023-21538

HIGH

Deserialization of Untrusted Data (CWE-502)

2023-01-10 secure@microsoft.com

Denial Of Service Deserialization Microsoft Fedora Powershell Net Fedoraproject

7.5

CVSS 3.1 · Vendor: microsoft

View

Vulnerability Assessment

Weakness	CWE CWE-502 OWASP Top 10:2025 A08:2025 - Software or Data Integrity Failures ASVS 5.0 V1 - Encoding and Sanitization Safe deserialization, type allowlists 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. Sign in to read
Impact	CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could execute arbitrary code through malicious serialized objects by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 2.7% exploitation probability (EPSS)

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AnalysisAI

.NET Denial of Service Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Avoid deserializing untrusted data. Use safe serialization formats (JSON). Implement integrity checks and type allowlists.

Affected Packages

nuget microsoft.netcore.app.runtime.linux-arm fix: 6.0.13

nuget microsoft.netcore.app.runtime.linux-arm64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.linux-musl-arm fix: 6.0.13

nuget microsoft.netcore.app.runtime.linux-musl-arm64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.linux-musl-x64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.linux-x64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.osx-arm64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.osx-x64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.win-arm fix: 6.0.13

nuget microsoft.netcore.app.runtime.win-arm64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.win-x64 fix: 6.0.13

nuget microsoft.netcore.app.runtime.win-x86 fix: 6.0.13

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 12 packages in nuget

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Deserialization of Untrusted Data (CWE-502), which allows attackers to execute arbitrary code through malicious serialized objects. Affected products include: Microsoft .Net, Microsoft Powershell, Fedoraproject Fedora.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (microsoft) · only source for this CVE.

CVSS VectorVendor: microsoft

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

DescriptionCVE.org

.NET Denial of Service Vulnerability

Threat Intelligence Overview

EPSS Score

2.7%

Top 16% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

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 2.7%

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· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +3

CVSS: +38

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Insecure Deserialization CRITICAL

Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.