CVE-2026-100223: Use-After-Free (CVSS 7.8)

Description

An elevation of privilege vulnerability exists when reparse points are created by sandboxed processes allowing sandbox escape. An attacker who successfully exploited the vulnerability could use the sandbox escape to elevate privileges on an affected system. To exploit the vulnerability, an attacker would first have to log on to the system, and then run a specially crafted application to take control over the affected system. The security update addresses the vulnerability by preventing sandboxed processes from creating reparse points targeting inaccessible files.

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CVSS v3.1 Score

7.8

HIGH

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

EPSS — Exploit Prediction

0.0032

Probability of exploitation

0.25%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-416 Use After Free

References

Other References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-100223

Frequently Asked Questions

What is CVE-2026-100223? +

An elevation of privilege vulnerability exists when reparse points are created by sandboxed processes allowing sandbox escape. An attacker who successfully exploited the vulnerability could use the sandbox escape to elevate privileges on an affected system. To exploit the vulnerability, an attacker would first have to log on to the system, and then run a specially crafted application to take control over the affected system. The security update addresses the vulnerability by preventing sandboxed processes from creating reparse points targeting inaccessible files. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-100223? +

CVE-2026-100223 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0032, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-100223? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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