CVE-2026-69277

Microsoft Local Security Authority (LSA) Server Elevation of Privilege Vulnerability

No known exploitation. EPSS puts it in the 25th percentile. No fix published yet.

CVSS 3.17.8High EPSS percentile25th0.3% chance in 30 days CISA KEVNot listedNo confirmed exploitation
No public exploit known FixNone yetNo fix or workaround published

Published 2026-09-08Updated 2026-09-24Sources: CVE.org, NVD

NVD CVE.org

What to do

No fixed build or workaround is published yet. Limit exposure and watch for a patch.

Steps

Written by AI from the record

Check which affected product you run (Windows 10/11 or Windows Server 2012–2025) and your exact OS version/build.
Compare your build to the fixed builds listed in Microsoft’s update for CVE-2026-69277 at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69277.
Install the Microsoft security update(s) that bring your machine to one of the fixed versions below:
- Windows 10: 10.0.14393.9512 or 10.0.17763.9245 or 10.0.19044.7725 or 10.0.19045.7725
- Windows 11: 10.0.22631.7582 or 10.0.26100.9445 or 10.0.26200.9445 or 10.0.28000.2954
- Windows Server 2012: 6.2.9200.26349
- Windows Server 2012 R2: 6.3.9600.23397
- Windows Server 2016: 10.0.14393.9512
- Windows Server 2019: 10.0.17763.9245
Reboot if your update process indicates a restart is needed, then re-check the OS build to confirm it matches a fixed version.

Vendor advisory Usually a quick update

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Stack-based buffer overflow in Microsoft Local Security Authority Server (lsasrv) allows an authorized attacker to elevate privileges locally.

In plain language

Written by AI from the record

This Windows security flaw lets a person who already has local access to your machine gain higher privileges; if you’re a typical small business, you should patch it urgently—especially on servers.

CVE-2026-69277 is a CWE-121 stack-based buffer overflow in Microsoft Local Security Authority Server (lsasrv) that can let an authenticated/authorized local attacker elevate privileges on affected Windows systems.

If you're affected

Full control of a workstation
Server account takeover
Wider malware spread
Service and system disruption

What is it

Think of lsasrv as a “security gatekeeper” Windows uses to enforce who can do what. This bug is like a mistake in that gatekeeper’s internal handling of data—so someone who already has a foothold on the machine could use it to climb to much higher permissions. With higher permissions, an attacker can often do far more harm and spread further inside your business.

Who is affected

This matters if you run or administer any of these Microsoft Windows versions: Windows 10, Windows 11, and Windows Server 2012 through Windows Server 2025. The weakness involves lsasrv and is a local privilege escalation, meaning it primarily becomes a real risk when an attacker already has local/authorized access (for example, access via a compromised account or machine foothold). It’s not the same as an internet-only remote attack—you’re most exposed where an intruder can get onto the device first.

How urgent is it

Treat this as urgent because it can turn a local foothold into full higher-privilege access on Windows systems. Even without confirmed wide public exploitation in the provided findings, the impact type (privilege escalation) is serious and the fixed versions are available—so you should prioritize patching to reduce the chance a local attacker can escalate.

What to do — in detail

Identify affected systems
- On each machine, confirm whether it’s one of: Windows 10, Windows 11, Windows Server 2012/2012 R2/2016/2019/2022/2025.
- Record the exact OS version/build number.
Determine whether you are already fixed
- Visit the Microsoft update guide for CVE-2026-69277: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69277
- Match your OS version/build against the fixed builds below and treat any older build as not yet fixed.
Upgrade/patch to the fixed build
- Apply the Microsoft security update that brings the system to one of the following fixed versions:
  - Windows 10 fixed in:
    - 10.0.14393.9512
    - 10.0.17763.9245
    - 10.0.19044.7725
    - 10.0.19045.7725
  - Windows 11 fixed in:
    - 10.0.22631.7582
    - 10.0.26100.9445
    - 10.0.26200.9445
    - 10.0.28000.2954
  - Windows Server 2012 fixed in:
    - 6.2.9200.26349
  - Windows Server 2012 R2 fixed in:
    - 6.3.9600.23397
  - Windows Server 2016 fixed in:
    - 10.0.14393.9512
  - Windows Server 2019 fixed in:
    - 10.0.17763.9245
Validate after patch
- Re-check the OS build number to confirm it matches a fixed version.
- Ensure the machine is fully restarted if your patch workflow requests it.
Temporary containment if patching is delayed
- Because the vulnerability involves local/authorized attacker conditions (attack path depends on local access), reduce chances of an attacker gaining local presence:
  - limit interactive logons for unnecessary accounts,
  - review recent sign-ins and unusual local activity,
  - enforce least privilege (remove local admin where possible).
- These steps don’t replace the patch, but they reduce the likelihood of local privilege escalation being useful.
What to monitor
- Watch for signs of an attacker already on the machine (e.g., unexpected admin activity, unusual process creation, and new local admin accounts), since privilege escalation attempts generally matter most after a foothold exists.

CISA KEV status

Not listed in CISA KEV (per provided findings).

Technical context

Severity and type: This is an elevation of privilege issue caused by a CWE-121 stack-based buffer overflow in Microsoft Local Security Authority Server (lsasrv). The provided traffic-light verdict is RED.

Attack conditions: The provided CVSS vector indicates local attack characteristics (AV:L) and no user interaction (UI:N). Practically, that means it’s primarily relevant when an attacker already has local/authorized access to the system and can trigger the vulnerable path.

Exploitation status: CISA KEV does not list this CVE in the provided findings, and there is no public exploit code on record in the provided findings. Press reporting mentions exploitation in the press without a clear dated claim.

Fix availability: Microsoft has published fixed builds per Windows version in the update guide linked in the findings. Use those fixed build numbers to confirm remediation.

KEV meaning here: Since it is not in CISA KEV (based on the provided findings), there’s no confirmation from that specific program of widespread verified exploitation; however, impact remains high because the flaw can convert local access into elevated privileges.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS25th

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.3% chance of exploitation activity in the next 30 days, which ranks it in the 25th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

7 events over 16 days, from the signal feeds we watch.

2026-09-24Record updated
2026-09-10OpenVAS check added
2026-09-09Record updated
2026-09-08Publishedweakness classified, att&ck mapped, record updated

Affected products

Microsoftcommercial · US

And 12 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 7.8 by NVD.

How it is reached

Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required LowRequires basic user-level privileges
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

Confidentiality HighTotal information disclosure — all data in the component is compromised
Integrity HighTotal loss of integrity — attacker can modify any data in the component
Availability HighTotal denial of service — the component is completely unavailable