CVE-2026-45491 — .NET Tampering Vulnerability

Executive Summary

Improper link resolution before file access ('link following') in .NET allows an unauthorized attacker to perform tampering locally.

Overview

5.5

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Exploitation Unlikely

MS Exploit Likelihood

Category Tampering

Released Jun 9 2026

Last Updated Jun 9 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00272 — 0.18742 percentile

NVD CVSS 5.5 MEDIUM — differs from MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

None

INTEGRITY

High

AVAILABILITY

None

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.4

EPSS Score

0.00272

probability of exploitation in the next 30 days

0.18742 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

10 affected products

Product	KB Article	Severity	Impact	Restart Required
.NET 10.0 installed on Linux	`5097148 (Security Update)`	Important	Tampering	Maybe
.NET 10.0 installed on Mac OS	`5097148 (Security Update)`	Important	Tampering	Maybe
.NET 10.0 installed on Windows	`5097148 (Security Update)`	Important	Tampering	Maybe
.NET 8.0	`5097149 (Security Update)`	Important	Tampering	Maybe
.NET 8.0 installed on Linux	`5097149 (Security Update)`	Important	Tampering	Maybe
.NET 8.0 installed on Mac OS	`5097149 (Security Update)`	Important	Tampering	Maybe
.NET 8.0 installed on Windows	`5097149 (Security Update)`	Important	Tampering	Maybe
.NET 9.0 installed on Linux	`5097150 (Security Update)`	Important	Tampering	Maybe
.NET 9.0 installed on Mac OS	`5097150 (Security Update)`	Important	Tampering	Maybe
.NET 9.0 installed on Windows	`5097150 (Security Update)`	Important	Tampering	Maybe

Patches

3 patches

Article	Type	Restart
`5097148`	Security Update	Maybe
`5097149`	Security Update	Maybe
`5097150`	Security Update	Maybe

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Anonymous, Ashmit Sharma, Ky0toFu, phrolo7a

References

MSRC Advisory MITRE NVD