CVE-2020-0603Network attack vector

Unauthenticated code execution via SignalR memory corruption

Published Jan 14, 2020 · Updated Aug 4, 2024

Memory corruption in SignalR for Microsoft ASP.NET Core 2.1, 3.0, and 3.1 allows remote attackers to execute code via crafted requests. SignalR's request-processing path mishandles objects in memory, but Microsoft has not disclosed the affected function or exact unsafe operation. Any unauthenticated network client that can reach an application using SignalR can trigger execution in the application's user context.

CVSS severity8.8
High
EPSS probability21.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in SignalR for Microsoft ASP.NET Core 2.1, 3.0, and 3.1 allows remote attackers to execute code via crafted requests. SignalR's request-processing path mishandles objects in memory, but Microsoft has not disclosed the affected function or exact unsafe operation. Any unauthenticated network client that can reach an application using SignalR can trigger execution in the application's user context.

The record

CVE
CVE-2020-0603
Published
Jan 14, 2020
Updated
Aug 4, 2024
Vendor
Microsoft
Product
ASP.NET Core
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 14, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.1
  2. Affected versionversion=3.0
  3. Affected versionversion=3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · ASP.NET Coreversion=2.1; version=3.0; version=3.1

Published CVSS scores

8.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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