CVE-2026-58649VulnerabilityPublished 15 Sep 2026Updated 29 Oct 2026

Red Hat Security Advisory: .NET 9.0 security, bug fix, and enhancement update

Affects Red Hat .NET 9.0Source GCVE Database

Mentioned vulnerabilities

CVE-2026-69806

Authoritative record:CVE-2026-58649· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium · fixed in Red Hat package updates : update Red Hat microsoft.netcore.app when convenient.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 29% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 17.14.40, 18.9.3

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Base metrics

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

Temporal metrics

Exploit Code Maturity: Unproven
Remediation Level: Official Fix
Report Confidence: Confirmed

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.
Exploit Code Maturity: Unproven: No exploit code is available, or an exploit is theoretical.
Remediation Level: Official Fix: A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.
Report Confidence: Confirmed: Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 8 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Microsoft Visual Studio 2022 version 17.14 to 17.14.40; Microsoft Visual Studio 2026 version 18.9 to 18.9.3; microsoft.netcore.app to 18.9.3 or 17.14.40.

Affected software

Product	Affected	Fixed in
Microsoft.NET 10.0	Affected =10.0.0	Fixed in–
Microsoft.NET 11.0	Affected =11.0.0	Fixed in–
Microsoft.NET 8.0	Affected =8.0.0	Fixed in–
Microsoft.NET 9.0	Affected =9.0.0	Fixed in–
MicrosoftMicrosoft Visual Studio 2022 version 17.14	Affected >=17.14.0 <17.14.40	Fixed in 17.14.40
MicrosoftMicrosoft Visual Studio 2026 version 18.9	Affected >=18.9.0 <18.9.3	Fixed in 18.9.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has released an official update for .NET 9.0 that includes SDK version 9.0.121 and runtime version 9.0.20 which address these vulnerabilities. Users should apply the update promptly following Red Hat's published instructions at https://access.redhat.com/articles/11258. No additional mitigation actions are indicated by the vendor advisory.

Description

.NET is a fast, lightweight and modular platform for creating cross platform applications that work on Linux, macOS and Windows. It particularly focuses on creating console applications, web applications and micro-services. .NET contains a runtime conforming to .NET Standards a set of framework libraries, an SDK containing compilers and a 'dotnet' application to drive everything. SDK version: 9.0.121 Runtime version: 9.0.20 Security Fix(es): * dotnet10.0: dotnet9.0: dotnet8.0: .NET Information Disclosure Vulnerability (CVE-2026-58649) * dotnet10.0: dotnet9.0: .NET Elevation of Privilege Vulnerability (CVE-2026-69806) Bug Fix(es) and Enhancement(s): * Update .NET 9.0 to SDK 9.0.121 and Runtime 9.0.20 [rhel-10.2.z] (JIRA:RHEL-252279) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Impact

Successful exploitation of CVE-2026-58649 could lead to unauthorized disclosure of information, while CVE-2026-69806 could allow an attacker to elevate privileges on the affected system. These vulnerabilities affect .NET runtime and SDK components on Red Hat Enterprise Linux 10. The overall security impact is rated as important by Red Hat. There are no reports of known exploits in the wild at this time.

Summary

This advisory addresses two security vulnerabilities in .NET versions 8.0, 9.0, and 10.0 on Red Hat Enterprise Linux 10. CVE-2026-58649 is an information disclosure vulnerability, and CVE-2026-69806 is an elevation of privilege vulnerability. Red Hat has released an update upgrading .NET to SDK 9.0.121 and runtime 9.0.20 to fix these issues. The advisory covers multiple architectures and product variants of Red Hat Enterprise Linux 10. The update is classified as important, and users are directed to apply the update as per Red Hat's guidance. No CVSS score is provided in the advisory, and no active exploitation has been reported.

CWE-346Origin Validation Error (opens in a new tab)
Class weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not properly verify that the source of data or communication is valid.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V14.5.2 (opens in a new tab)
V14.5.3 (opens in a new tab)
V1.4.4 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Exploit Script-Based APIs (opens in a new tab)
Application API Message Manipulation via Man-in-the-Middle (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-200Exposure of Sensitive Information to an Unauthorized Actor (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #20OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Separation of Privilege
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
Subverting Environment Variable Values (opens in a new tab)
ICMP Echo Request Ping (opens in a new tab)
TCP SYN Scan (opens in a new tab)
Enumerate Mail Exchange (MX) Records (opens in a new tab)
DNS Zone Transfers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Sep 2026, 03:13 UTC

WeaknessesCWE-346, CWE-200

Technical details

References

Community reviews

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