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CVE-2026-42899VulnerabilityPublished Updated

Red Hat Security Advisory: .NET 9.0 security update

Affects Red Hat .NET 9.0Source GCVE Database

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Authoritative record:CVE-2026-42899· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in Red Hat package updates : patch Red Hat microsoft.net soon.

Data as of 6 Nov 2026, 02:06 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 10.0.8, 8.0.27, 9.0.16
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 5 Nov 2026.

What to do

Upgrade .NET to 10.0.8 (10.0) or 8.0.27 (8.0) or 9.0.16 (9.0).

Affected software

ProductAffectedFixed in
Microsoft.NET 10.0Affected
  • >=10.0.0 <10.0.8
Fixed in
  • 10.0.8
Microsoft.NET 8.0Affected
  • >=8.0.0 <8.0.27
Fixed in
  • 8.0.27
Microsoft.NET 9.0Affected
  • >=9.0.0 <9.0.16
Fixed in
  • 9.0.16
NuGetmicrosoft.netpkg:nuget/microsoft.netOther threatsAffected
  • =10.0.0
Fixed in–

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 fixed versions: .NET SDK 9.0.117 and .NET Runtime 9.0.16. Users should update to these versions as soon as possible. Detailed update instructions are available from Red Hat's advisory. Since official fixes are available, applying these updates fully mitigates the vulnerability.

Description

.NET 9.0 contained a security vulnerability that could cause an infinite loop, allowing an attacker to cause a denial of service. Red Hat has released updated versions of the .NET SDK (9.0.117) and .NET Runtime (9.0.16) that address this issue. The vulnerability is identified as CVE-2026-42899 and is rated with a high severity impact by Red Hat. This affects Red Hat Enterprise Linux 9.6 Extended Update Support and related products. Users are advised to apply the provided updates to remediate the vulnerability.

References

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