Improper input validation in MySQL Server - CVE-2026-21948

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Main Vulnerability Database Vulnerabilities #VU121740

Improper input validation in MySQL Server - CVE-2026-21948

Published: January 20, 2026


Vulnerability identifier: #VU121740
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-21948
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote privileged user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper input validation within the Server: Optimizer component in MySQL Server. A remote privileged user can exploit this vulnerability to perform a denial of service (DoS) attack.


Affected software

MySQL Server
Anolis OS
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for x86_64
openEuler
Ubuntu
mecab
mecab-ipadic-EUCJP
mecab-ipadic
mysql-8.0 (Ubuntu package)
mysql-common
mysql-test
mysql-server
mysql-libs
mysql-errmsg
mysql-devel
mysql
mysql-config
mysql-debuginfo
mysql-debugsource
mysql-help
mysql (Red Hat package)
mysql8.4 (Red Hat package)

How to mitigate CVE-2026-21948

Install updates from vendor's website.

mecab - update to 0.996-2
mecab-ipadic-EUCJP - update to 2.7.0.20070801-17.0.1
mecab-ipadic - update to 2.7.0.20070801-17.0.1
mysql-8.0 (Ubuntu package) - addressed in versions 8.0.45-0ubuntu0.20.04.1+esm2, 8.0.45-0ubuntu0.22.04.1, 8.0.45-0ubuntu0.24.04.1, 8.4.8-0ubuntu0.25.10.1
mysql-common - update to 8.0.45-1
mysql-test - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql-server - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql-libs - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql-errmsg - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql-devel - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql-common - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql - addressed in versions 8.0.45-1, 8.0.45-1.0.1
mysql-test - update to 8.0.45-1
mysql - update to 8.0.45-1
mysql-config - update to 8.0.45-1
mysql-debuginfo - update to 8.0.45-1
mysql-debugsource - update to 8.0.45-1
mysql-devel - update to 8.0.45-1
mysql-errmsg - update to 8.0.45-1
mysql-help - update to 8.0.45-1
mysql-libs - update to 8.0.45-1
mysql-server - update to 8.0.45-1
mysql (Red Hat package) - update to 8.0.45-1.el9_7
mysql8.4 (Red Hat package) - update to 8.4.8-1.el10_1

External References

Related Security Bulletins