CVE-2026-42010 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Jun 3, 2026
CBL-Mariner Releases
Vendor-listed releases
3.8.3-10
3.8.3-11
CISA KEVNot listedBased on the latest collected catalog
EPSS1.1%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-42010?
A flaw was found in gnutls. Servers configured with RSA-PSK (Rivest–Shamir–Adleman – Pre-Shared Key) wrongfully matched usernames containing a NUL character with truncated usernames.
A remote attacker could exploit this by sending a specially crafted username, leading to an authentication bypass. This vulnerability allows an attacker to gain unauthorized access by circumventing the authentication process.