No exploitation reportedFix available

CVE-2021-25220

Q: Is CVE-2021-25220 actively exploited?

Active exploitation of CVE-2021-25220 has not been confirmed. Its EPSS score was 3.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-25220?

CVE-2021-25220 has a CVSS v3 base score of 6.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N.

No exploitation reported by the sources we read.

Published2022-03-23
Fixed in19.3
WeaknessCWE-444

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

BIND 9.11.0 -> 9.11.36 9.12.0 -> 9.16.26 9.17.0 -> 9.18.0 BIND Supported Preview Editions: 9.11.4-S1 -> 9.11.36-S1 9.16.8-S1 -> 9.16.26-S1 Versions of BIND 9 earlier than those shown - back to 9.1.0, including Supported Preview Editions - are also believed to be affected but have not been tested as they are EOL. The cache could become poisoned with incorrect records leading to queries being made to the wrong servers, which might also result in false information being returned to clients.

Timeline

dates in UTC

2022-03-2313:15CVE publishedNVD

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-2021-25220?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-25220?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Juniper junosversion to verify

Branch	Affected	Fixed in	Source
19.3	< 19.3	19.3	NVD
19.3	= 19.3	no fix published	NVD
19.4	= 19.4	no fix published	NVD
20.2	= 20.2	no fix published	NVD
20.3	= 20.3	no fix published	NVD
20.4	= 20.4	no fix published	NVD
21.1	= 21.1	no fix published	NVD
21.2	= 21.2	no fix published	NVD
21.3	= 21.3	no fix published	NVD
21.4	= 21.4	no fix published	NVD
22.1	= 22.1	no fix published	NVD
22.2	= 22.2	no fix published	NVD

Isc bind

Branch	Affected	Fixed in	Source
9.x	≥ 9.12.0, < 9.16.27	9.16.27	NVD
9.16	≥ 9.16.8, < 9.16.27	9.16.27	NVD
9.11	≥ 9.11.0, < 9.11.37	9.11.37	NVD
9.11	≥ 9.11.4, < 9.11.37	9.11.37	NVD
9.x	≥ 9.17.0, ≤ 9.18.0	no fix published	NVD

Fedoraproject fedora

Branch	Affected	Fixed in	Source
34.x	= 34	no fix published	NVD
35.x	= 35	no fix published	NVD
36.x	= 36	no fix published	NVD

9 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:9all versions · fixed in 32:9.16.23-5.el9_1and 9 other packages
bindAlmaLinux:8all versions · fixed in 32:9.11.36-5.el8and 16 other packages
bind9.16AlmaLinux:8all versions · fixed in 32:9.16.23-0.9.el8.1and 8 other packages
dhcp-relayAlmaLinux:9all versions · fixed in 12:4.4.2-17.b1.el9and 3 other packages

Full record on NVD

Fix

Update Juniper junos to 19.3

Advisories and patches

cert-portal.siemens.comPatch
kb.isc.orgMitigation · Vendor Advisory

Detection

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

Sources

CNACVSS 3.16.8read 2026-10-23
NVDCVSS 3.16.8read 2026-10-23
NVDCVSS 2.04read 2026-10-23
NVDweakness (CWE)CWE-444read 2026-10-23
FIRST EPSSEPSS score3.5 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N
Published: 2022-03-23
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-25220?

Is CVE-2021-25220 actively exploited?

Active exploitation of CVE-2021-25220 has not been confirmed. Its EPSS score was 3.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-25220?

CVE-2021-25220 has a CVSS v3 base score of 6.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N.

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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 ».

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