Executive Summary

Name CVE-2021-25216 First vendor Publication 2021-04-29
Vendor Cve Last vendor Modification 2021-06-07

Security-Database Scoring CVSS v3

Cvss vector : CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Overall CVSS Score 9.8
Base Score 9.8 Environmental Score 9.8
impact SubScore 5.9 Temporal Score 9.8
Exploitabality Sub Score 3.9
Attack Vector Network Attack Complexity Low
Privileges Required None User Interaction None
Scope Unchanged Confidentiality Impact High
Integrity Impact High Availability Impact High
Calculate full CVSS 3.0 Vectors scores

Security-Database Scoring CVSS v2

Cvss vector : (AV:N/AC:M/Au:N/C:P/I:P/A:P)
Cvss Base Score 6.8 Attack Range Network
Cvss Impact Score 6.4 Attack Complexity Medium
Cvss Expoit Score 8.6 Authentication None Required
Calculate full CVSS 2.0 Vectors scores


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.

Original Source

Url : http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-25216

CWE : Common Weakness Enumeration

% Id Name
100 % CWE-617 Reachable Assertion

CPE : Common Platform Enumeration

Application 649
Os 2

Sources (Detail)

Source Url
CONFIRM https://kb.isc.org/v1/docs/cve-2021-25215
DEBIAN https://www.debian.org/security/2021/dsa-4909
MISC https://www.zerodayinitiative.com/advisories/ZDI-21-657/
MLIST http://www.openwall.com/lists/oss-security/2021/04/29/1

Alert History

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Date Informations
2021-08-28 01:43:02
  • Multiple Updates
2021-06-07 21:23:14
  • Multiple Updates
2021-05-21 13:22:56
  • Multiple Updates
2021-05-12 21:23:18
  • Multiple Updates
2021-05-04 21:23:26
  • Multiple Updates
2021-05-01 21:23:09
  • Multiple Updates
2021-04-30 12:10:37
  • Multiple Updates
2021-04-30 12:10:31
  • Multiple Updates
2021-04-30 01:10:35
  • Multiple Updates
2021-04-30 01:10:28
  • Multiple Updates
2021-04-30 00:22:50
  • Multiple Updates
2021-04-29 21:23:11
  • Multiple Updates
2021-04-29 09:22:50
  • First insertion