CVE-2026-101802: 
MySQL vulnerability analysis and mitigation

CVE-2026-101802 is a Denial of Service vulnerability in the Parser component of Oracle MySQL Server and MySQL Cluster. It was disclosed on October 20, 2026, as part of Oracle's Critical Patch Update (CPU) for October 2026. Affected versions include MySQL Server 8.4.0–8.4.12, 9.7.0–9.7.3, and 26.7.0–26.7.1, and MySQL Cluster 8.0.0–8.0.49, 8.4.0–8.4.12, 9.7.0–9.7.3, and 26.7.0–26.7.1. The vulnerability carries a CVSS v3.1 base score of 6.5 (Medium) (Oracle Advisory). The vulnerability was reported to Oracle by researcher Muhammad Daffa (Oracle Advisory).

The vulnerability resides in the Server: Parser component of MySQL Server and MySQL Cluster, classified as an availability-impacting flaw (CWE category: improper input handling leading to resource exhaustion or crash). A low-privileged attacker with network access can send specially crafted SQL queries that trigger a hang or frequently repeatable crash of the database server. The attack requires no user interaction and is accessible via multiple protocols, making it straightforward to exploit once valid credentials are obtained. No detailed technical write-up or public proof-of-concept code has been identified at this time (Oracle Advisory).

Successful exploitation results in a complete Denial of Service (DoS) of the affected MySQL Server or MySQL Cluster instance, causing it to hang or crash repeatedly. There is no confidentiality or integrity impact — the vulnerability is limited to availability. In environments where MySQL underpins critical applications or services, repeated crashes could cause significant service disruption and potential data unavailability for dependent systems (Oracle Advisory).

The vulnerability is described as "easily exploitable" by Oracle, requiring only low privileges and network access with no user interaction. As of the disclosure date, there is no public proof-of-concept exploit and no evidence of in-the-wild exploitation (Oracle Advisory). The EPSS score is 0.0, and the vulnerability has not been added to the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been reported.

Oracle has released patches for this vulnerability as part of the October 2026 Critical Patch Update. Administrators should upgrade to patched versions of MySQL Server (beyond 8.4.12, 9.7.3, or 26.7.1) and MySQL Cluster (beyond 8.0.49, 8.4.12, 9.7.3, or 26.7.1) as specified in the Oracle advisory. As interim mitigations, Oracle recommends restricting network access to MySQL instances to trusted clients only, implementing query timeouts and resource limits, and removing unnecessary privileges from database users. Oracle strongly advises against relying on network-blocking workarounds as a long-term solution (Oracle Advisory).