CVE-2023-35391

Information disclosure through SignalR Redis backplane

Published Aug 8, 2023 · Updated Aug 10, 2026

Information disclosure in ASP.NET Core SignalR on affected .NET and Visual Studio releases allows local attackers to read application data. Microsoft identifies the SignalR Redis backplane as the vulnerable locus but has not published the incorrect operation that exposes data. Reachability requires an affected application configured to use the Redis backplane; no integrity or availability impact is reported.

CVSS severity6.2
Medium
EPSS probability1.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in ASP.NET Core SignalR on affected .NET and Visual Studio releases allows local attackers to read application data. Microsoft identifies the SignalR Redis backplane as the vulnerable locus but has not published the incorrect operation that exposes data. Reachability requires an affected application configured to use the Redis backplane; no integrity or availability impact is reported.

The record

CVE
CVE-2023-35391
Published
Aug 8, 2023
Updated
Aug 10, 2026
Vendor
Microsoft
Product
.NET 6.0
Classifications
CWE-200
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 8, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 2026Record 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=6.0.0 <6.0.21

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · .NET 6.0version=6.0.0 <6.0.21
Microsoft · Microsoft Visual Studio 2022 version 17.6version=17.6.0 <17.6.6
Microsoft · Microsoft Visual Studio 2022 version 17.4version=17.4.0 <17.4.10
Microsoft · ASP.NET Coreversion=2.0 <2.1.40
Microsoft · Microsoft Visual Studio 2022 version 17.2version=17.2.0 <17.2.18
Microsoft · .NET 7.0version=7.0.0 <7.0.10

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
6.2Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor

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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