Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
None
Attack Vector
Network
1

CVE-2021-25216

Disclosure Date: April 28, 2021 •
CVE-2021-25216 CVSS v3 Base Score: 9.8
Add MITRE ATT&CK tactics and techniques that apply to this CVE.
Discovery
Techniques
Validation
Validated
Execution
Techniques
Validation
Validated

Description

In BIND 9.5.0 –> 9.11.29, 9.12.0 –> 9.16.13, and versions BIND 9.11.3-S1 –> 9.11.29-S1 and 9.16.8-S1 –> 9.16.13-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 –> 9.17.1 of the BIND 9.17 development branch, BIND servers are vulnerable if they are running an affected version and are configured to use GSS-TSIG features. In a configuration which uses BIND’s default settings the vulnerable code path is not exposed, but a server can be rendered vulnerable by explicitly setting values for the tkey-gssapi-keytab or tkey-gssapi-credential configuration options. Although the default configuration is not vulnerable, GSS-TSIG is frequently used in networks where BIND is integrated with Samba, as well as in mixed-server environments that combine BIND servers with Active Directory domain controllers. For servers that meet these conditions, the ISC SPNEGO implementation is vulnerable to various attacks, depending on the CPU architecture for which BIND was built: For named binaries compiled for 64-bit platforms, this flaw can be used to trigger a buffer over-read, leading to a server crash. For named binaries compiled for 32-bit platforms, this flaw can be used to trigger a server crash due to a buffer overflow and possibly also to achieve remote code execution. We have determined that standard SPNEGO implementations are available in the MIT and Heimdal Kerberos libraries, which support a broad range of operating systems, rendering the ISC implementation unnecessary and obsolete. Therefore, to reduce the attack surface for BIND users, we will be removing the ISC SPNEGO implementation in the April releases of BIND 9.11 and 9.16 (it had already been dropped from BIND 9.17). We would not normally remove something from a stable ESV (Extended Support Version) of BIND, but since system libraries can replace the ISC SPNEGO implementation, we have made an exception in this case for reasons of stability and security.

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CVSS V3 Severity and Metrics
Base Score:
9.8 Critical
Impact Score:
5.9
Exploitability Score:
3.9
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
None
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
BIND9 9.5.0 through versions before 9.11.31
BIND9 9.12.0 through versions before 9.16.14
BIND9 9.11.3-S1 through versions before 9.11.31-S1
BIND9 9.16.8-S1 through versions before 9.16.14-S1
BIND9 9.17.0 through versions before 9.17.2
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • debian,
  • isc,
  • netapp,
  • siemens

Products

  • active iq unified manager -,
  • aff 500f firmware -,
  • aff a250 firmware -,
  • bind,
  • bind 9.10.5,
  • bind 9.10.7,
  • bind 9.11.12,
  • bind 9.11.21,
  • bind 9.11.27,
  • bind 9.11.29,
  • bind 9.11.3,
  • bind 9.11.5,
  • bind 9.11.6,
  • bind 9.11.7,
  • bind 9.11.8,
  • bind 9.16.11,
  • bind 9.16.13,
  • bind 9.16.8,
  • bind 9.9.12,
  • bind 9.9.13,
  • bind 9.9.3,
  • cloud backup -,
  • debian linux 10.0,
  • debian linux 9.0,
  • h300e firmware -,
  • h300s firmware -,
  • h410s firmware -,
  • h500e firmware -,
  • h500s firmware -,
  • h700e firmware -,
  • h700s firmware -,
  • sinec infrastructure network services
Technical Analysis