Security Digest · Vulnerability record
CVE-2026-105016: Microsoft Security Advisory CVE-2026-105016 - Microsoft QUIC Remote Code Execution Vulnerability
Heap-based buffer overflow in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
CVSS 9.8 Critical EPSS 1.0% · p62
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 1.0%, percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
Microsoft.Native.Quic.MsQuic.Schannel(NuGet) = 2.5.11-ci.156755675, fixed in 2.5.11-ci.159417053. Check your lockfile, including transitive dependencies.
What it is
Heap-based buffer overflow in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
From the GitHub advisory
Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft QUIC as used by .NET 8.0, .NET 9.0, .NET 10.0, and .NET 11 RC2 on Windows. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
A crafted IPv6 QUIC packet can reach the Microsoft QUIC HTTP/3 path without authentication or user interaction and trigger remote code execution.
Announcement
Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/446
Weakness type: CWE-122.
Product: Microsoft.Native.Quic.MsQuic.Schannel (NuGet) · Assigned by: microsoft · Published: 2026-10-13
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| NuGet | Microsoft.Native.Quic.MsQuic.Schannel | = 2.5.11-ci.156755675 | 2.5.11-ci.159417053 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Microsoft | .NET 10.0 | 10.0.0 < 10.0.14 |
| Microsoft | .NET 11.0 | 11.0.0 < 11.0.0-rc.2.26504.105 |
| Microsoft | .NET 8.0 | 8.0.0 < 8.0.32 |
| Microsoft | .NET 9.0 | 9.0.0 < 9.0.21 |
| Microsoft | Microsoft Visual Studio 2022 version 17.14 | 17.14.0 < 17.14.42 |
| Microsoft | Microsoft Visual Studio 2026 version 18.10 | 18.10.0 < 18.10.4 |
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 < 10.0.22631.7652 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 < 10.0.22631.7652 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 < 10.0.26100.9711 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 < 10.0.26200.9711 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoft | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.99% probability of exploitation activity in the next 30 days; percentile 62.
Timeline
- — CVE record published by microsoft
- — GitHub-reviewed advisory GHSA-5gjq-3f94-rcf7 published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- Microsoft QUIC Remote Code Execution Vulnerability msrc.microsoft.com
Vulnerability records
- GitHub Advisory GHSA-5gjq-3f94-rcf7 github.com
- CVE.org record CVE-2026-105016 cve.org
- NVD entry CVE-2026-105016 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com