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VulnerabilityPublished

CVE-2025-36854: Microsoft .NET 6.0 · Use After Free

Affects Microsoft .NET 6.0Source CVE Database V5

0

Mentioned vulnerabilities

Not known to be exploited · CVSS 8.1 High · end of life, no fix coming : replace or isolate Microsoft .NET 6.0; no fix will be released.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
None coming – the product is end of life
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 8 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

No fix will be released: Microsoft .NET 6.0 is end of life. Replace it, or isolate it from untrusted networks until you can.

Affected software

ProductAffectedFixed in
Microsoft .NET 6.0Affected
  • =6.0.0
Fixed in–

AI-suggested

Given the EOL status of the affected ASP.NET versions, the primary mitigation is to upgrade to a supported .NET version that addresses this vulnerability. Organizations should prioritize migrating applications from .NET 6.0 EOL versions to the latest supported releases (e.g., .NET 7 or later) that receive security updates. For self-contained applications, recompilation and redeployment targeting secure versions are essential. In environments where immediate upgrade is not feasible, organizations should implement strict network segmentation and firewall rules to limit exposure of vulnerable services, especially those using HTTP/3. Employ runtime application self-protection (RASP) and web application firewalls (WAF) with custom rules to detect and block suspicious HTTP/3 stream closure patterns. Conduct thorough code reviews and testing to identify and eliminate unsafe memory handling patterns in custom ASP.NET code. Monitor logs and network traffic for anomalous behavior indicative of exploitation attempts. Finally, establish an incident response plan tailored to potential RCE attacks exploiting this vulnerability to minimize damage if an incident occurs.

Description

A vulnerability ( CVE-2024-38229 https://www.cve.org/CVERecord ) exists in EOL ASP.NET when closing an HTTP/3 stream while application code is writing to the response body, a race condition may lead to use-after-free, resulting in Remote Code Execution. Per CWE-416: Use After Free https://cwe.mitre.org/data/definitions/416.html , Use After Free is when a product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. This issue affects EOL ASP.NET 6.0.0 <= 6.0.36 as represented in this CVE, as well as 8.0.0 <= 8.0.8, 9.0.0-preview.1.24081.5 <= 9.0.0.RC.1 as represented in  CVE-2024-38229 https://www.cve.org/CVERecord . 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 only represents End Of Life (EOL) software components. The vendor, Microsoft, has indicated there will be no future updates nor support provided upon inquiry.

References

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