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CVE-2021-25216

76
FAUCET Score

CVE-2021-25216 is a critical vulnerability affecting BIND 9.x versions configured to use GSS-TSIG features, impacting products from Debian, ISC, NetApp, and Siemens. This flaw allows for a buffer over-read or overflow, leading to denial of service on 64-bit platforms and potential remote code execution on 32-bit platforms. With a CVSS score of 9.8 (Critical) and an EPSS score indicating high exploitability, it presents a significant risk. While there is no known active exploitation or public exploit code, the vulnerability has garnered substantial community discussion and media coverage, highlighting its potential impact.

Impacted Technologies

VendorProductVersion(s)CPE
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
>= 9.0.0, < 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:*:*:*:*:-:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
82.37%
Probability of exploitation in next 30 days
EPSS Percentile
99.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.8237 is in the 98th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

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

Vendor Advisories (3)

microsoft2021-May/CVE-2021-25216

CVE-2021-25216

May 11, 2021
redhatCVE-2021-25216Important

bind: Vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a buffer overflow attack

Apr 28, 2021
microsoft2021-Apr/CVE-2021-25216Critical

A second vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a buffer overflow attack

Apr 13, 2021

References

cert-portal.siemens.com / productcert/pdf/ssa-389290.pdf
PatchThird Party Advisory
kb.isc.org / v1/docs/cve-2021-25215
Not Applicable
lists.debian.org / debian-lts-announce/2021/05/msg00001.html
Mailing ListThird Party Advisory
security.netapp.com / advisory/ntap-20210521-0006
Third Party Advisory
debian.org / security/2021/dsa-4909
Third Party Advisory
zerodayinitiative.com / advisories/ZDI-21-657
Third Party AdvisoryVDB Entry
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