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CVE-2021-25214

24
FAUCET Score

CVE-2021-25214 is a denial-of-service vulnerability affecting multiple versions of ISC BIND 9, including Debian, Fedora, NetApp, and Siemens products. A remote attacker can trigger a named process termination by sending a malformed IXFR to a vulnerable server, leading to a failed assertion upon the next zone refresh. Rated Medium severity (CVSS 6.5), this flaw requires low privileges and network access but no user interaction, resulting in high availability impact. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 9.8.5, <= 9.8.8CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
>= 9.9.3, < 9.11.31CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
>= 9.12.0, < 9.16.15CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
>= 9.17.0, < 9.17.12CPE matchmatch criteria
cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
9.9.3CPE matchmatch criteria
cpe:2.3:a:isc:bind:9.9.3:s1:*:*:supported_preview:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.99%
Probability of exploitation in next 30 days
EPSS Percentile
92.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0599 is in the 98th percentile among its peer group of 21,977 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (6)

microsoftpatch availablevia msrc
Product: 17071-16820Fixed in: 9.16.15-1
microsoftpatch availablevia msrc
Product: cm1 bind 9.16.15-1 on CBL Mariner 1.0Fixed in: 9.16.15-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 9.16.15-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 9.16.15-1
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: bind-32:9.11.4-26.P2.el7_9.7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: bind-32:9.11.26-6.el8
View patch

Vendor Advisories (3)

microsoft2021-May/CVE-2021-25214

CVE-2021-25214

May 11, 2021
redhatCVE-2021-25214Moderate

bind: Broken inbound incremental zone update (IXFR) can cause named to terminate unexpectedly

Apr 28, 2021
microsoft2021-Apr/CVE-2021-25214Moderate

A broken inbound incremental zone update (IXFR) can cause named to terminate unexpectedly

Apr 13, 2021

References

cert-portal.siemens.com / productcert/pdf/ssa-389290.pdf
PatchThird Party Advisory
kb.isc.org / v1/docs/cve-2021-25214
Vendor Advisory
lists.debian.org / debian-lts-announce/2021/05/msg00001.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/VEC2XG4Q2ODTN2C4CGXEIXU3EUTBMK7L
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/ZDSRPCJQ7MZC6CENH5PO3VQOFI7VSWBE
security.netapp.com / advisory/ntap-20210521-0006
Third Party Advisory
debian.org / security/2021/dsa-4909
Third Party Advisory
openwall.com / lists/oss-security/2021/04/29/1
Mailing ListThird Party Advisory
openwall.com / lists/oss-security/2021/04/29/2
Mailing ListThird Party Advisory
openwall.com / lists/oss-security/2021/04/29/3
Mailing ListThird Party Advisory
openwall.com / lists/oss-security/2021/04/29/4
Mailing ListThird Party Advisory