What is CVE-2026-21637?

CVE-2026-21637 is a security advisory published by Microsoft Security Response Center (MSRC) with Medium severity. HackerOne: CVE-2026-21637 TLS PSK/ALPN Callback Exceptions Bypass Error Handlers

Which CVE IDs does CVE-2026-21637 cover?

CVE-2026-21637 covers the following CVE IDs: CVE-2026-21637. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-21637?

CVE-2026-21637 has a CVSS v3 base score of 7.5, published by Microsoft Security Response Center (MSRC).

CVE-2026-21637MediumCVSS 7.5

HackerOne: CVE-2026-21637 TLS PSK/ALPN Callback Exceptions Bypass Error Handlers

Vendor

Microsoft Security Response Center (MSRC)

Published

June 2, 2026

Last Modified

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🔗 CVE IDs covered (1)

CVE-2026-21637 →

🔗 CVE IDs covered (1)

📋 Description