{"id":"CVE-2026-101623","kind":"vulnerability","aliases":["CVE-2026-101623"],"related":[],"title":"MySQL Server: Optimizer flaw lets a privileged user crash the server","description":"Vulnerability in the MySQL Server, MySQL Cluster product of Oracle MySQL (component: Server: Optimizer).  Supported versions that are affected are MySQL Server: 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; 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. Easily exploitable vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server, MySQL Cluster.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server, MySQL Cluster. 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).","summary":"A flaw in the MySQL Server optimizer lets a high-privileged attacker over the network trigger a hang or repeatable crash of MySQL Server and MySQL Cluster. The impact is denial of service only, with no confidentiality or integrity loss stated.","severity":"medium","cvss":4.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["databases","mysql","package","self-hosted"],"not_affected_if":["no-high-privilege-accounts-exposed","unaffected-version"],"how_to_check":"- Run `SELECT VERSION();` on each MySQL Server and MySQL Cluster node and compare against the affected ranges: MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; MySQL Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1.","fix":"- Upgrade MySQL Server and MySQL Cluster to a release outside the affected ranges, using the patched version named in Oracle's April 2026 Critical Patch Update advisory (version not stated in the sources).","status":"open","published_at":"2026-10-20T22:18:16+00:00","first_seen_at":"2026-10-23T21:57:22+00:00","triaged_at":"2026-10-25T04:31:33+00:00","updated_at":"2026-10-25T04:31:33+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T04:31:33Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade MySQL Server and MySQL Cluster to a release outside the affected ranges, using the patched version named in Oracle's April 2026 Critical Patch Update advisory (version not stated in the sources).","reach":"network","title":"MySQL Server: Optimizer flaw lets a privileged user crash the server","impact":"low","summary":"A flaw in the MySQL Server optimizer lets a high-privileged attacker over the network trigger a hang or repeatable crash of MySQL Server and MySQL Cluster. The impact is denial of service only, with no confidentiality or integrity loss stated.","category":"package","nicknames":[],"who_cares":["mysql","databases","self-hosted"],"confidence":0.7,"needs_auth":"yes","worst_case":"Server hangs or crashes repeatedly, causing a complete denial of service.","analyst_note":"","how_to_check":"- Run `SELECT VERSION();` on each MySQL Server and MySQL Cluster node and compare against the affected ranges: MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; MySQL Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1.","needs_analyst":false,"not_affected_if":["unaffected-version","no-high-privilege-accounts-exposed"],"who_is_affected":"Deployments running the affected MySQL Server or MySQL Cluster versions where a high-privileged account can reach the server over the network. Systems on unaffected versions, or where only tightly controlled administrator accounts can connect, have lower exposure.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000673,"input_tokens":3585,"output_tokens":628,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-101623':14A,17A '-2026':13A,16A '/av':160C '26.7.0':92C,103C '26.7.1':93C,104C '3.1':150C,159C '4.9':153C '8.0.0':96C '8.0.49':97C '8.4.0':88C,98C '8.4.12':89C,99C '9.7.0':90C,100C '9.7.3':91C,101C 'abil':133C 'access':114C 'affect':84C 'allow':108C 'attack':36B,111C,125C 'avail':154C 'base':151C 'caus':135C 'cluster':51B,72C,95C,123C,148C 'complet':142C 'compon':77C 'compromis':119C 'confidenti':61B 'crash':9A,45B,141C 'cve':12A,15A 'cvss':149C,156C,158C 'databas':18B 'denial':55B 'dos':143C 'easili':105C 'exploit':106C 'flaw':4A,25B 'frequent':139C 'h':168C 'h/ui':163C 'hang':42B,137C 'high':34B,109C 'high-privileg':33B 'host':23B 'impact':53B,155C 'integr':63B 'l/pr':162C 'let':5A,31B 'loss':64B 'multipl':116C 'mysql':1A,19B,28B,47B,50B,69C,71C,76C,86C,94C,120C,122C,145C,147C 'n/a':167C 'n/ac':161C 'n/i':166C 'n/s':164C 'network':39B,113C 'optim':3A,30B,79C 'oracl':75C 'packag':20B 'privileg':7A,35B,110C 'product':73C 'protocol':117C 'repeat':44B,140C 'result':130C 'score':152C 'self':22B 'self-host':21B 'server':2A,11A,29B,48B,70C,78C,87C,121C,146C 'servic':57B 'state':65B 'success':124C 'support':80C 'trigger':40B 'u/c':165C 'unauthor':132C 'user':8A 'vector':157C 'version':81C 'via':115C 'vulner':66C,107C,128C","nicknames":[],"mitigations":[],"who_affected":"Deployments running the affected MySQL Server or MySQL Cluster versions where a high-privileged account can reach the server over the network. Systems on unaffected versions, or where only tightly controlled administrator accounts can connect, have lower exposure.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-20T22:18:16+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","cvss_by":"secalert_us@oracle.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-101623","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-101623","severity":null,"published_at":"2026-10-20T22:18:16+00:00","modified_at":"2026-10-21T19:16:50+00:00","first_seen_at":"2026-10-23T21:57:22+00:00","fetched_at":"2026-10-23T22:28:59+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}