Vulnerability in Microsoft .Net 6.0

CVE-2025-36855

A vulnerability ( CVE-2025-21176 https://www.cve.org/CVERecord ) exists in DiaSymReader.dll due to buffer over-read. Per CWE-126: Buffer Over-read https://cwe.mitre.org/data/definitions/126.html , Buffer Over-read is when a product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer. This issue affects EOL ASP.NET 6.0.0 <= 6.0.36 as represented in this CVE, as well as 8.0.0 <= 8.0.11 & <= 9.0.0 as represented in CVE-2025-21176. Additionally, if you've deployed self-contained applications https://docs.microsoft.com/dotnet/core/deploying/#self-contained-deployments-scd  targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed. NOTE: This CVE affects only End Of Life (EOL) software components. The vendor, Microsoft, has indicated there will be no future updates nor support provided upon inquiry.

EPSS: 0.007 (50.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-36855?
CVE-2025-36855 is a high-severity vulnerability in Microsoft .Net 6.0, classified under Buffer Over-read. CVSS score: 8.8/10. Published 2025-09-08.
How severe is CVE-2025-36855?
High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2025-36855 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.