No exploitation reportedFix available

CVE-2021-2166

Q: Is CVE-2021-2166 actively exploited?

Active exploitation of CVE-2021-2166 has not been confirmed. Its EPSS score was 4.9% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-2166?

CVE-2021-2166 has a CVSS v3 base score of 4.9 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2021-04-22
Fixed in10.5.10 · 10.4.19 · 10.3.29 · 10.2.38

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

Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: DML). Supported versions that are affected are 5.7.33 and prior and 8.0.23 and prior. Easily exploitable vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.1 Base Score 4.9 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

Timeline

dates in UTC

2021-04-2222:15CVE 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-2021-2166?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-2166?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

MariaDB

Branch	Affected	Fixed in	Source
10.5	≥ 10.5.0, < 10.5.10	10.5.10	NVD · OSV
10.4	≥ 10.4.0, < 10.4.19	10.4.19	NVD · OSV
10.3	≥ 10.3.0, < 10.3.29	10.3.29	NVD · OSV
10.2	≥ 10.2.0, < 10.2.38	10.2.38	NVD · OSV

Fedoraproject fedora

Branch	Affected	Fixed in	Source
32.x	= 32	no fix published	NVD
33.x	= 33	no fix published	NVD
34.x	= 34	no fix published	NVD

MySQL

Branch	Affected	Fixed in	Source
5.7	≥ 5.7.0, ≤ 5.7.33	no fix published	NVD
8.0	≥ 8.0, ≤ 8.0.23	no fix published	NVD

4 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

galeraAlmaLinux:8all versions · fixed in 25.3.34-4.module_el8.5.0+2632+14ced695
galeraAlmaLinux:8all versions · fixed in 25.3.34-4.module_el8.6.0+2867+72759d2f
galeraAlmaLinux:8all versions · fixed in 26.4.9-4.module_el8.5.0+2637+d11efe18
galeraAlmaLinux:8all versions · fixed in 26.4.9-4.module_el8.6.0+2761+593e5e59
JudyAlmaLinux:8all versions · fixed in 1.0.5-18.module_el8.5.0+2632+14ced695
JudyAlmaLinux:8all versions · fixed in 1.0.5-18.module_el8.5.0+2637+d11efe18
JudyAlmaLinux:8all versions · fixed in 1.0.5-18.module_el8.6.0+2761+593e5e59
JudyAlmaLinux:8all versions · fixed in 1.0.5-18.module_el8.6.0+2867+72759d2f

10 more package ranges on OSV.dev

Full record on NVD

Fix

Update MariaDB to 10.5.10 · 10.4.19 · 10.3.29 · 10.2.38

Advisories and patches

www.oracle.comVendor Advisory

Detection

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

Sources

CISA-ADPSSVC decisionnone2024-09-26
OpenCVESSVC decisionnone—
CNACVSS 3.14.9read 2026-10-23
NVDCVSS 2.04read 2026-10-23
FIRST EPSSEPSS score4.9 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Published: 2021-04-22
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-2166?

Is CVE-2021-2166 actively exploited?

Active exploitation of CVE-2021-2166 has not been confirmed. Its EPSS score was 4.9% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-2166?

CVE-2021-2166 has a CVSS v3 base score of 4.9 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.

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