CVE-2026-55960: Un-negotiated Raw Public Key (RFC 7250) accepted in place of X.509, bypassing chain validation

highCVSS 7.5CVE-2026-55960

CSIRTS triage

Other

What: Un-negotiated Raw Public Key is accepted, bypassing chain validation.
Who is affected: Systems using the affected cryptographic libraries.
Urgency: High urgency due to a CVSS score of 7.5, indicating significant risk.
Action: Implement the recommended security updates for the cryptographic libraries.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.5
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55960

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-559600.14% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 4% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-55960	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

highCVE-2026-55960: Un-negotiated Raw Public Key (RFC 7250) accepted in place of an X.509 certificate, bypassing c…nvd

Recent advisories for Un-negotiated Raw Public

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-55960: Un-negotiated Raw Public Key (RFC 7250) accepted in place of an X.509 certificate, bypassing c…nvd · 2026-06-25