CVE-2021-25214— A broken inbound incremental zone update (IXFR) can cause named to terminate unexpectedly
Quick assessment
Affected
ISC BIND9
Exploitation
High exploitation probability; assess promptly
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
ISC BIND是美国ISC公司的一套实现了DNS协议的开源软件。 ISC BIND 存在安全漏洞，该漏洞导致接收已命名服务器无意中从区域数据库中删除有问题的区域的SOA记录。
Possible ATT&CK Techniques 1 AI
T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2021-25214
Vulnerability Information
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Vulnerability Title
A broken inbound incremental zone update (IXFR) can cause named to terminate unexpectedly
Source: CVE Program / CVE List V5
Vulnerability Description
In BIND 9.8.5 -> 9.8.8, 9.9.3 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.9.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND 9 Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.11 of the BIND 9.17 development branch, when a vulnerable version of named receives a malformed IXFR triggering the flaw described above, the named process will terminate due to a failed assertion the next time the transferred secondary zone is refreshed.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
ISC BIND 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
ISC BIND是美国ISC公司的一套实现了DNS协议的开源软件。 ISC BIND 存在安全漏洞，该漏洞导致接收已命名服务器无意中从区域数据库中删除有问题的区域的SOA记录。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2021-25214
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Vendor Advisories for CVE-2021-25214 (3)
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https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf x_refsource_CONFIRM
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https://security.netapp.com/advisory/ntap-20210521-0006/ x_refsource_CONFIRM
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Mailing List Discussions for CVE-2021-25214 (6)
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https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZDSRPCJQ7MZC6CENH5PO3VQOFI7VSWBE/ vendor-advisory x_refsource_FEDORA
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https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VEC2XG4Q2ODTN2C4CGXEIXU3EUTBMK7L/ vendor-advisory x_refsource_FEDORA
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Other References for CVE-2021-25214 (1)
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https://kb.isc.org/v1/docs/cve-2021-25214 x_refsource_CONFIRM
Same Patch Batch · ISC · 2021-04-29 · 3 CVEs total
| CVE-2021-25216 | 8.1 HIGH | A second vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a b |
| CVE-2021-25215 | 7.5 HIGH | An assertion check can fail while answering queries for DNAME records that require the DNA |
IV. Related Vulnerabilities
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Same vendor: ISC
-
CVE-2026-13321
DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field -
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Unexpected exit in certain situations with NSEC and NSEC3 bo -
CVE-2026-12617
Record ordering based unexpected exit with CNAME or DNAME -
CVE-2026-11721
Cache poisoning possible with label count discrepancy, RRSIG -
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Potential memory usage beyond configured limits
V. Comments for CVE-2021-25214
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