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Findings

CVE-2026-42010

Gnutls: gnutls: authentication bypass via nul character in username

Published May 7, 2026 · updated Oct 14, 2026

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.

Timeline

Detection, updates, and resolution for this record.

  1. May 7, 2026 · Catalog

    Detected

    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

  2. Oct 14, 2026 · Catalog

    Updated

    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

Affected

  • vendor Red Hat Red Hat Enterprise Linux 10version unspecified
  • vendor Red Hat Red Hat Enterprise Linux 10.0 Extended Update Supportversion unspecified
  • vendor Red Hat Red Hat Enterprise Linux 8version unspecified
  • vendor Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportversion unspecified
  • vendor Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onversion unspecified

Sources

  • CIRCL Vulnerability LookupCVE-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 authe

    vulnerability.circl.lu

References

CVE-2026-42010 · ZeroDay Findings