CVE tracker / CVE-2026-34343

CVE-2026-34343

CVE-2026-34343 is the Windows Application Identity (AppID) Subsystem Elevation of Privilege Vulnerability. Microsoft rates it Important, CVSS 7.8. It is not in CISA's Known Exploited Vulnerabilities catalog. Published May 12, 2026.

Risk summary

HighElevation of Privilege
7.8
CVSS v3 base
0.3%
EPSS: chance of exploitation in 30 days
High
Severity
Important
Microsoft's rating
Less Likely
Microsoft: exploitation
No
In CISA KEV

Microsoft describes it: “Heap-based buffer overflow in Windows Application Identity (AppID) Subsystem allows an authorized attacker to elevate privileges locally.”

How to fix it

Microsoft lists 31 affected products and the update that fixes each:

What Microsoft changed

Details

Weakness
CWE-122: Heap-based Buffer Overflow
Publicly disclosed (Microsoft)
No
Exploited (Microsoft)
No
Known exploited (CISA KEV)
Not listed
Published
May 12, 2026
Last revised
May 12, 2026

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References

Microsoft Security Update Guide NVD CVE record CWE

From Microsoft, CISA, NVD and FIRST data; the Microsoft details were read when this page was opened. Check the references above before you act.