CVE tracker / CVE-2026-62899

CVE-2026-62899

CVE-2026-62899 is the .NET Security Feature Bypass Vulnerability. Microsoft rates it Important, CVSS 5.9. It is not in CISA's Known Exploited Vulnerabilities catalog. Published August 11, 2026.

Risk summary

MediumSecurity Feature Bypass
5.9
CVSS v3 base
0.7%
EPSS: chance of exploitation in 30 days
Medium
Severity
Important
Microsoft's rating
Less Likely
Microsoft: exploitation
No
In CISA KEV

Microsoft describes it: “Inconsistent interpretation of http requests ('http request/response smuggling') in .NET allows an unauthorized attacker to bypass a security feature over a network.”

How to fix it

Microsoft lists 10 affected products and the update that fixes each:

What Microsoft changed

Details

Weakness
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Publicly disclosed (Microsoft)
No
Exploited (Microsoft)
No
Known exploited (CISA KEV)
Not listed
Published
August 11, 2026
Last revised
August 11, 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.