How severe is CVE-2025-21521?

CVE-2025-21521 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-21521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-21521?

CVE-2025-21521 affects Oracle Mysql Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-21521?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-21521 have an EU (EUVD) identifier?

Yes. CVE-2025-21521 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-2510.

When was CVE-2025-21521 published?

CVE-2025-21521 was published on 2025-01-21 and last updated on 2026-06-17.

CVE-2025-21521

CVE-2025-21521 is a high-severity vulnerability in Oracle Mysql Server with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-2510
Weakness: CWE-770
Affected product: Oracle Mysql Server
Published: 2025-01-21
Last modified: 2026-06-17

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).

Frequently asked questions

What is CVE-2025-21521?: 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).
How severe is CVE-2025-21521?: CVE-2025-21521 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-21521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-21521?: CVE-2025-21521 affects Oracle Mysql Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-21521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-21521 have an EU (EUVD) identifier?: Yes. CVE-2025-21521 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-2510.
When was CVE-2025-21521 published?: CVE-2025-21521 was published on 2025-01-21 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:oracle:mysql_server:*:*:*:*:*:*:*:*

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