dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-54982

HIGH · 8.8 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 10.0.14393.9339 / 10.0.17763.9020 or later.
See remediation →
93/100
Remediation priority · Urgent
No privileges Zero-click Patch available 5 weeks old

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 · unedited
Integer underflow (wrap or wraparound) in Reliable Multicast Transport Driver (RMCAST) allows an unauthorized attacker to execute code over an adjacent network.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 1mo ago

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 confidence

Integer underflow vulnerability in the Reliable Multicast Transport Driver (RMCAST) allows an adjacent network attacker to cause memory corruption leading to arbitrary code execution. The integer wraparound occurs during arithmetic operations in the driver, enabling heap or stack-based memory corruption.

MitigationRestrict network access to systems running RMCAST, apply vendor-specific patches when released, and disable RMCAST if not required in the environment.

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
Windows 10 1607Operating system
Affected:< 10.0.14393.9339
Windows 10 1809Operating system
Affected:< 10.0.17763.9020
Windows 10 21h2Operating system
Affected:< 10.0.19044.7548
Windows 10 22h2Operating system
Affected:< 10.0.19045.7548
Windows 11 24h2Operating system
Affected:< 10.0.26100.8875
Windows 11 25h2Operating system
Affected:< 10.0.26200.8875
Windows 11 26h1Operating system
Affected:< 10.0.28000.2525
Windows Server 2012Operating system
Affected:all versions= r2

CVSS 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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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 checks

Work through these to decide whether this CVE applies to you.

  1. Check Windows version against affected ranges
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' and compare the build number to the vulnerable version thresholds listed in the CVE
    Affected if The build number is lower than any of these thresholds: 14393.9339 (1607), 17763.9020 (1809), 19044.7548 (21h2), 19045.7548 (22h2), 26100.8875 (24h2), 26200.8875 (25h2), 28000.2525 (26h1)
  2. Confirm Windows Server 2012/R2 exposure
    Run 'systeminfo' and verify the OS is Windows Server 2012 or Windows Server 2012 R2; these versions are listed as all versions affected
    Affected if The system is Windows Server 2012 or Windows Server 2012 R2 (any build)
  3. Verify RMCAST driver is loaded
    Run 'sc query rmcast' or check driver list via 'driverquery /v | findstr -i rmcast' to determine if the Reliable Multicast Transport Driver is present and running
    Affected if The RMCAST driver service exists and is in a running or stopped-but-present state (the driver does not need to be actively processing to be exploitable if loaded)
  4. Check multicast protocol binding status
    Run 'netsh interface ipv4 show config' or inspect network adapter properties in ncpa.cpl to see if IP multicast is enabled on any active network interfaces
    Affected if Multicast is enabled on any network adapter (this indicates RMCAST could be invoked by adjacent attackers)
  5. Inspect RMCAST driver file version
    Locate the rmcast.sys driver file (typically in C:\Windows\System32\drivers\) and check its file version via right-click Properties or 'wmic datafile where "name='C:\\Windows\\System32\\drivers\\rmcast.sys'" get version'
    Affected if The driver file exists and its version is below the patched version for the corresponding Windows build (comparison needed against vendor patch when released)

You are affected if you run any of the listed Windows versions with a build below the threshold AND the RMCAST driver is present on the system, regardless of whether it is actively processing traffic.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 10.0.14393.9339 / 10.0.17763.9020 / 10.0.19044.7548 or later
Fixed in 10.0.14393.933910.0.17763.902010.0.19044.7548
Vendor patch msrc.microsoft.com →
Interim mitigation

Restrict network access to systems running RMCAST, apply vendor-specific patches when released, and disable RMCAST if not required in the environment.

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-54982 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-54982 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

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.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data