CVE-2026-42836
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 · uneditedConcurrent execution using shared resource with improper synchronization ('race condition') in Function Discovery Service (fdwsd.dll) allows an authorized attacker to elevate privileges locally.
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 confidenceA race condition vulnerability exists in the Function Discovery Service (fdwsd.dll) in Windows. The flaw involves improper synchronization when accessing shared resources, allowing an authorized local attacker to manipulate timing to elevate privileges to higher permissions than normally granted.
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< 10.0.14393.9234< 10.0.17763.8880< 10.0.19044.7417< 10.0.19045.7417< 10.0.22631.7219< 10.0.26100.8655< 10.0.26200.8655< 10.0.28000.2269CVSS 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
- Local
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/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 checksWork through these to decide whether this CVE applies to you.
-
Check Windows versionRun 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to identify the installed Windows version and build numberAffected if The build number is lower than any of these thresholds: 14393.9234 (1607), 17763.8880 (1809), 19044.7417 (21h2), 19045.7417 (22h2), 22631.7219 (23h2), 26100.8655 (24h2), 26200.8655 (25h2), or 28000.2269 (26h1)
-
Locate fdwsd.dll fileSearch for fdwsd.dll in system directories: 'dir /s C:\Windows\System32\fdwsd.dll' or 'Get-ChildItem -Path C:\Windows -Filter fdwsd.dll -Recurse -ErrorAction SilentlyContinue'Affected if The file exists on the system, as the vulnerability resides in this DLL
-
Get fdwsd.dll versionRight-click fdwsd.dll, select Properties, then Details tab, or run 'powershell (Get-Item "C:\Windows\System32\fdwsd.dll").VersionInfo'Affected if The file version is lower than the patched version for your specific Windows build, though Microsoft typically patches via security bulletins rather than incrementing DLL versions directly
-
Check Function Discovery Service statusRun 'services.msc' and locate "Function Discovery Service" or run 'sc query fdPHost' from command promptAffected if The service is running (the race condition occurs when the service is active and handling discovery requests)
-
Review security event logs for suspicious activityOpen Event Viewer, navigate to Windows Logs > Security, and look for unexpected process creation or privilege escalation events around the time of service operationsAffected if Unusual events involving fdwsd.dll or the fdPHost service are found, which may indicate exploitation attempts
Your system is likely affected if it runs a Windows version with a build number lower than the thresholds listed and has fdwsd.dll present, especially if the Function Discovery Service is enabled and running.
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.
dbcve · scoped10.0.14393.923410.0.17763.888010.0.19044.7417
Apply the vendor patch when available. If the Function Discovery Service is not required in the environment, consider disabling it to reduce the attack surface. Monitor for suspicious process activity and privilege escalation attempts.
Upgrade to the specific fixed build for your Windows release: 10.0.14393.9234 (Win10 1607), 10.0.17763.8880 (Win10 1809), 10.0.19044.7417 (Win10 21h2), 10.0.19045.7417 (Win10 22h2), 10.0.22631.7219 (Win11 23h2), 10.0.26100.8655 (Win11 24h2), 10.0.26200.8655 (Win11 25h2), or 10.0.28000.2269 (Win11 26
- Identify the current Windows version by running 'winver' or 'systeminfo' in Command Prompt
- Determine which Windows 10 or 11 release and build number you are currently running
- For Windows 10 1607: Upgrade to build 10.0.14393.9234 or later via Windows Update or Windows Server Update Services
- For Windows 10 1809: Upgrade to build 10.0.17763.8880 or later via Windows Update or Windows Server Update Services
- For Windows 10 21h2: Upgrade to build 10.0.19044.7417 or later via Windows Update
- For Windows 10 22h2: Upgrade to build 10.0.19045.7417 or later via Windows Update
- For Windows 11 23h2: Upgrade to build 10.0.22631.7219 or later via Windows Update
- For Windows 11 24h2: Upgrade to build 10.0.26100.8655 or later via Windows Update
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation3.0 h
- Testing3.0 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 $3,440.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-42836 — 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-2026-42836 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
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.
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
- No spam, self-promotion, credentials, or personal data