CVE-2025-21521 Denial of service in MySQL Server
Unauthenticated attackers can cause a complete denial of service in MySQL Server via network access, requiring immediate patching.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-21521?
CVE-2025-21521 is a high-severity denial of service vulnerability in Oracle Mysql Server, published on 21 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Thread Pooling). Supported versions that are affected are 8.0.39 and prior, 8.4.2 and prior and 9.0.1 and prior. Easily exploitable vulnerability allows unauthenticated 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 7.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-770
Which versions are affected by CVE-2025-21521?
It affects 1 product.
Linux distribution packages (40)
mysql8.4 Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-common Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-debuginfo Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-debugsource Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-devel Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-devel-debuginfo Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-errmsg Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-libs Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-libs-debuginfo Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-server Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-server-debuginfo Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-test Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-test-data Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mysql8.4-test-debuginfo Red Hat:enterprise_linux:10.0 | All versions | 0:8.4.4-2.el10 |
mecab Red Hat:rhel_aus:8.2::appstream | All versions | 0:0.996-1.module+el8.0.0+3898+e09bb8de.9 |
mecab-debuginfo Red Hat:rhel_aus:8.2::appstream | All versions | 0:0.996-1.module+el8.0.0+3898+e09bb8de.9 |
mecab-debugsource Red Hat:rhel_aus:8.2::appstream | All versions | 0:0.996-1.module+el8.0.0+3898+e09bb8de.9 |
mecab-ipadic Red Hat:rhel_aus:8.2::appstream | All versions | 0:2.7.0.20070801-16.module+el8.0.0+3898+e09bb8de |
mecab-ipadic-EUCJP Red Hat:rhel_aus:8.2::appstream | All versions | 0:2.7.0.20070801-16.module+el8.0.0+3898+e09bb8de |
mysql Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-common Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-debuginfo Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-debugsource Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-devel Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-devel-debuginfo Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-errmsg Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-libs Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-libs-debuginfo Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-server Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-server-debuginfo Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-test Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mysql-test-debuginfo Red Hat:rhel_aus:8.2::appstream | All versions | 0:8.0.40-1.module+el8.2.0+22898+0bdd8c5b.4 |
mecab Red Hat:rhel_aus:8.4::appstream | All versions | 0:0.996-1.module+el8.0.0+3898+e09bb8de.9 |
mecab-debuginfo Red Hat:rhel_aus:8.4::appstream | All versions | 0:0.996-1.module+el8.0.0+3898+e09bb8de.9 |
mecab-debugsource Red Hat:rhel_aus:8.4::appstream | All versions | 0:0.996-1.module+el8.0.0+3898+e09bb8de.9 |
mecab-ipadic Red Hat:rhel_aus:8.4::appstream | All versions | 0:2.7.0.20070801-16.module+el8.0.0+3898+e09bb8de |
mecab-ipadic-EUCJP Red Hat:rhel_aus:8.4::appstream | All versions | 0:2.7.0.20070801-16.module+el8.0.0+3898+e09bb8de |
mysql Red Hat:rhel_aus:8.4::appstream | All versions | 0:8.0.40-1.module+el8.4.0+22899+4f2ca788.1 |
mysql-common Red Hat:rhel_aus:8.4::appstream | All versions | 0:8.0.40-1.module+el8.4.0+22899+4f2ca788.1 |
mysql-debuginfo Red Hat:rhel_aus:8.4::appstream | All versions | 0:8.0.40-1.module+el8.4.0+22899+4f2ca788.1 |
Products include Oracle Mysql Server.
How do I fix CVE-2025-21521?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-21521 being exploited?
There is no known exploitation of CVE-2025-21521 in the wild and no public exploit code.
Other vulnerabilities in Oracle Mysql Server
Sources
Also known as AZL-63039, GHSA-2rgw-wmwq-m2w3, RHBA-2025:5321, RHSA-2025:1755, RHSA-2025:1756, RHSA-2025:1757 and 5 more.