Microsoft Security Advisory CVE-2026-62898 – .NET Information Disclosure Vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-62898: 1.03% estimated exploitation activity in the next 30 days; percentile 63.67 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft QUIC. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A use after free in Microsoft QUIC allows an unauthorized attacker to disclose information over a network. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/426 CVSS Details - Version: 3.1 - Severity: High - Score: 7.5 - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C - Weakness: CWE-416: Use After Free Affected Platforms - Platforms: Windows - Architectures: All <a name="affected-packages"</aAffected Packages The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below <a name=".NET 10"</a.NET 10 Package name | Affected version | Patched version ------------ | ---------------- | -------------------------…

Published by the source

11 Aug 2026, 18:28 UTC

Last modified by the source

17 Aug 2026, 08:10 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-c494-m2fq-59mx

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-c494-m2fq-59mx

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# Patch Next advisory brief: CVE-2026-62898

Advisory: Microsoft Security Advisory CVE-2026-62898 – .NET Information Disclosure Vulnerability
IDs: CVE-2026-62898, GHSA-c494-m2fq-59mx
Record: https://patchnext.com/advisories/cve-2026-62898 (revision 2, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.netcore.app.runtime.win-x86 10.0.11, 9.0.19, 8.0.30; microsoft.netcore.app.runtime.win-arm64 10.0.11, 9.0.19, 8.0.30; microsoft.netcore.app.runtime.win-x64 10.0.11, 9.0.19, 8.0.30. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.netcore.app.runtime.win-x86: affected >= 10.0.0, <= 10.0.10; >= 9.0.0, <= 9.0.18; >= 8.0.0, <= 8.0.29; fixed in 9.0.19, 10.0.11, 8.0.30
- NuGet microsoft.netcore.app.runtime.win-arm64: affected >= 10.0.0, <= 10.0.10; >= 9.0.0, <= 9.0.18; >= 8.0.0, <= 8.0.29; fixed in 9.0.19, 10.0.11, 8.0.30
- NuGet microsoft.netcore.app.runtime.win-x64: affected >= 10.0.0, <= 10.0.10; >= 9.0.0, <= 9.0.18; >= 8.0.0, <= 8.0.29; fixed in 9.0.19, 10.0.11, 8.0.30

## Suggested inspection (read-only)
- NuGet microsoft.netcore.app.runtime.win-x86: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.win-arm64: check the installed version with your package manager.
- NuGet microsoft.netcore.app.runtime.win-x64: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on microsoft.netcore.app.runtime.win-x86, microsoft.netcore.app.runtime.win-arm64, microsoft.netcore.app.runtime.win-x64.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-c494-m2fq-59mx (OSV record GHSA-c494-m2fq-59mx lists affected ranges: NuGet microsoft.netcore.app.runtime.win-arm64 >=10.0.0 =9.0.0 =8.0.0 =10.0.0 =9.0.0 =8.0.0 =10.0.0 =9.0.0 =8.0.0 <8.0.30 (fixed))
- Verified: https://github.com/advisories/GHSA-c494-m2fq-59mx (GitHub-reviewed advisory GHSA-c494-m2fq-59mx lists affected ranges: NuGet microsoft.netcore.app.runtime.win-arm64 >=10.0.0 =9.0.0 =8.0.0 =10.0.0 =9.0.0 =8.0.0 =10.0.0 =9.0.0 =8.0.0 <=8.0.29)

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