No exploitation reportedFix available

CVE-2021-25219

Q: Is CVE-2021-25219 actively exploited?

Active exploitation of CVE-2021-25219 has not been confirmed. Its EPSS score was 11.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-25219?

CVE-2021-25219 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

No exploitation reported by the sources we read.

Published2021-10-27
Fixed in9.17.19 · 9.16.22 · 9.11.36

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

In BIND 9.3.0 -> 9.11.35, 9.12.0 -> 9.16.21, and versions 9.9.3-S1 -> 9.11.35-S1 and 9.16.8-S1 -> 9.16.21-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.18 of the BIND 9.17 development branch, exploitation of broken authoritative servers using a flaw in response processing can cause degradation in BIND resolver performance. The way the lame cache is currently designed makes it possible for its internal data structures to grow almost infinitely, which may cause significant delays in client query processing.

Timeline

dates in UTC

2021-10-2721:15CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-25219?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-25219?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Isc bind

Branch	Affected	Fixed in	Source
9.17	≥ 9.17.0, < 9.17.19	9.17.19	NVD
9.x	≥ 9.12.0, < 9.16.22	9.16.22	NVD
9.x	≥ 9.3.0, < 9.11.36	9.11.36	NVD
9.9	= 9.9.3	no fix published	NVD
9.9	= 9.9.12	no fix published	NVD
9.9	= 9.9.13	no fix published	NVD
9.10	= 9.10.5	no fix published	NVD
9.10	= 9.10.7	no fix published	NVD
9.11	= 9.11.3	no fix published	NVD
9.11	= 9.11.5	no fix published	NVD
9.11	= 9.11.6	no fix published	NVD
9.11	= 9.11.7	no fix published	NVD

Debian debian linux

Branch	Affected	Fixed in	Source
9.0	= 9.0	no fix published	NVD
10.0	= 10.0	no fix published	NVD
11.0	= 11.0	no fix published	NVD

Fedoraproject fedora

Branch	Affected	Fixed in	Source
33.x	= 33	no fix published	NVD
34.x	= 34	no fix published	NVD
35.x	= 35	no fix published	NVD

12 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

bindAlmaLinux:8all versions · fixed in 32:9.11.36-3.el8and 16 other packages

Full record on NVD

Fix

Update Isc bind to 9.17.19 · 9.16.22 · 9.11.36

Advisories and patches

cert-portal.siemens.comPatch
kb.isc.orgVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.15.3read 2026-10-23
NVDCVSS 3.15.3read 2026-10-23
NVDCVSS 2.05read 2026-10-23
FIRST EPSSEPSS score11.0 %read 2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Published: 2021-10-27
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-25219?

Is CVE-2021-25219 actively exploited?

Active exploitation of CVE-2021-25219 has not been confirmed. Its EPSS score was 11.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-25219?

CVE-2021-25219 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Running bind? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this product CISA KEV additions, October 2026 Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database