CVE-2026-21941: Oracle MySQL Server · Uncontrolled Resource Consumption
Affects Oracle MySQL ServerSource CVE Database V5
Not known to be exploited · CVSS 4.9 Medium.
Data as of 26 Oct 2026, 08:30 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 20 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Oracle CorporationMySQL Server | Affected
| Fixed in– |
Mavencom.oracle/mysql-serverpkg:maven/com.oracle/mysql-serverOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
1. Apply Oracle's official patches immediately once they are released for the affected MySQL versions. 2. Restrict network access to MySQL servers using firewalls and network segmentation to limit exposure to trusted hosts and administrators only. 3. Enforce strict access controls and monitor privileged account usage to prevent unauthorized or unnecessary high-privilege access. 4. Implement robust logging and alerting for MySQL server crashes or hangs to detect exploitation attempts early. 5. Consider deploying MySQL servers behind VPNs or secure tunnels to reduce attack surface. 6. Regularly audit and update MySQL versions to supported releases with security fixes. 7. Use database connection proxies or gateways that can provide additional filtering and rate limiting to mitigate potential DoS attempts. 8. Conduct internal penetration testing focusing on privilege escalation and DoS scenarios to validate defenses. 9. Prepare incident response plans specifically addressing database availability issues to minimize downtime impact.
Description
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 8.0.0-8.0.44, 8.4.0-8.4.7 and 9.0.0-9.5.0. 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).