CVE-2026-56186
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedOut-of-bounds read in Windows Schannel allows an authorized attacker to disclose information over a network.
In the news
Third-party coverage- Microsoft July 2026 Patch Tuesday fixes massive 570 flaws, 3 zero-days
- Microsoft CVE Summary - Bleeping Computer
Surfaced from public web coverage — external links open in a new tab.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceAn out-of-bounds read vulnerability exists in Windows Schannel, the Windows SSL/TLS security provider. This allows an authorized attacker on the network to read memory beyond allocated buffers, potentially exposing sensitive information such as credentials, session tokens, or other data in memory.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 10.0.14393.9339< 10.0.17763.9020< 10.0.19044.7548< 10.0.19045.7548< 10.0.26100.8875< 10.0.26200.8875< 10.0.28000.2525all versions= r2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check Windows build versionOpen Command Prompt or PowerShell and run `winver` to see the build number, or use `systeminfo | findstr /C:"OS Version"` or `Get-ComputerInfo | Select-Object OsVersion, OsBuildNumber`Affected if The build number is below the threshold for your Windows version (14393.9339 for 1607, 17763.9020 for 1809, 19044.7548 for 21h2, 19045.7548 for 22h2, 26100.8875 for 11 24h2, 26200.8875 for 11 25h2, 28000.2525 for 11 26h1)
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Identify exact Windows releaseRun `winver` or `Get-ComputerInfo | Select-Object WindowsProductName, WindowsVersion` to confirm whether you are on Windows 10 1607, 1809, 21h2, 22h2 or Windows 11 24h2, 25h2, 26h1Affected if You cannot determine your exact Windows release to map it to the correct build threshold
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Confirm Schannel is in useSchannel (schannel.dll) is the default TLS/SSL provider on Windows. Check that applications are using TLS/SSL by inspecting running processes or checking registry key HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNELAffected if Schannel is disabled or replaced by a third-party TLS provider, though this is uncommon on standard Windows installations
Your system is affected if it runs Windows 10 1607, 1809, 21h2, 22h2, Windows 11 24h2, 25h2, 26h1, or Windows Server 2012/2012 R2 with a build number below the specified thresholds for your version, and Schannel TLS/SSL is enabled (the default configuration).
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data10.0.14393.933910.0.17763.902010.0.19044.7548
Apply Microsoft security updates for Schannel when available; ensure TLS/SSL traffic is monitored and network access to affected systems follows least-privilege principles.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-56186 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-56186 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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