Security Digest · Vulnerability record
CVE-2026-62815: Microsoft QUIC: Remote Code Execution Vulnerability
Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
CVSS 10.0 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.OpenSSL(NuGet) >= 2.5.3, < 2.5.10, fixed in 2.5.10;Microsoft.Native.Quic.MsQuic.Schannel(NuGet) >= 2.5.3, < 2.5.10, fixed in 2.5.10;Microsoft.Native.Quic.MsQuic.OpenSSL(NuGet) < 2.4.19, fixed in 2.4.19;Microsoft.Native.Quic.MsQuic.Schannel(NuGet) < 2.4.19, fixed in 2.4.19. Check your lockfile, including transitive dependencies.
What it is
Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
From the GitHub advisory
Summary Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
Details
New network path creations and removals triggered by incoming packets can lead to a pointer invalidation.
Patches
- Guard path promotion e0f55b5
Weakness type: CWE-416.
Product: Microsoft.Native.Quic.MsQuic.OpenSSL (NuGet) · Assigned by: microsoft · Published: 2026-08-11
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| NuGet | Microsoft.Native.Quic.MsQuic.OpenSSL | >= 2.5.3, < 2.5.10 | 2.5.10 |
| NuGet | Microsoft.Native.Quic.MsQuic.Schannel | >= 2.5.3, < 2.5.10 | 2.5.10 |
| NuGet | Microsoft.Native.Quic.MsQuic.OpenSSL | < 2.4.19 | 2.4.19 |
| NuGet | Microsoft.Native.Quic.MsQuic.Schannel | < 2.4.19 | 2.4.19 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 < 10.0.22631.7517 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 < 10.0.22631.7517 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 < 10.0.26100.9168 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 < 10.0.26200.9168 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 < 10.0.28000.2704 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 < 10.0.20348.5499 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 < 10.0.26100.33296 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 < 10.0.26100.33296 |
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 | 4.0 | 10.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: none (no login)
- User interaction: none
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): 0.97% probability of exploitation activity in the next 30 days; percentile 62.
Timeline
- — CVE record published by microsoft
- — GitHub-reviewed advisory GHSA-92f5-vc22-8j33 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-92f5-vc22-8j33 github.com
- CVE.org record CVE-2026-62815 cve.org
- NVD entry CVE-2026-62815 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com