EUVD-2026-44083
GHSA-c4wh-pp4w-w8fw
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local EoP by an authenticated low-priv user (AV:L/PR:L); use-after-free race gives AC:H; successful escalation yields full C:H/I:H/A:H with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Backup Engine allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Backup Engine affects Windows 10 (21H2, 22H2) and Windows 11 (24H2, 25H2, 26H1), where a use-after-free (CWE-416) memory-corruption flaw lets an already-authorized local user with low privileges elevate to higher rights. No public exploit identified at time of analysis, and it is not listed in CISA KEV; Microsoft rates it 7.0 (High), reflecting meaningful impact tempered by high attack complexity. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to already possess valid low-privileged local access to the target host (PR:L, AV:L) and the ability to invoke or influence Windows Backup Engine operations that trigger the vulnerable free/use sequence; it cannot be launched remotely or by an unauthenticated party. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H tells a nuanced story: exploitation is local (AV:L), requires an already-authenticated low-privileged user (PR:L), needs no user interaction (UI:N), but carries High attack complexity (AC:H) - typically indicating a race condition or non-deterministic heap state the attacker must win, which is consistent with a use-after-free. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker who has already gained a low-privileged foothold on a Windows host - for example through phishing, a compromised standard user account, or a low-integrity process - triggers backup-engine operations to force the use-after-free and grooms the heap to reuse the freed object. By winning the associated race, they corrupt memory to execute code in a higher-privilege context, escalating from limited user to full control of the machine. … |
| Remediation | Patch available per vendor advisory - apply the Microsoft security update for CVE-2026-50406 delivered through the monthly cumulative/quality update for your specific build, as documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50406 (the input does not state a discrete KB or file version, so consult the MSRC guide for the exact build number matching your edition). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory all Windows 10 (versions 21H2, 22H2) and Windows 11 (versions 24H2, 25H2, 26H1) systems; flag those running Windows Backup Engine in production environments. …
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Same weakness CWE-416 – Use After Free
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External POC / Exploit Code
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