{"id":"CVE-2026-101789","kind":"vulnerability","aliases":["CVE-2026-101789"],"related":[],"title":"MySQL Server optimizer flaw lets low-privileged users crash the database","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 low 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 6.5 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).","summary":"A flaw in the MySQL Server optimizer lets an attacker with low-privilege database access trigger a hang or repeatable crash. The result is a denial of service against MySQL Server and MySQL Cluster, with no data read or changed according to the CVSS vector.","severity":"medium","cvss":6.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["databases","mysql","package","self-hosted"],"not_affected_if":["no-untrusted-db-accounts","unaffected-version"],"how_to_check":"- Run `SELECT VERSION();` in MySQL and compare against the affected ranges: MySQL Server 8.4.0 to 8.4.12, 9.7.0 to 9.7.3, 26.7.0 to 26.7.1; MySQL Cluster 8.0.0 to 8.0.49, 8.4.0 to 8.4.12, 9.7.0 to 9.7.3, 26.7.0 to 26.7.1.","fix":"- Upgrade MySQL Server or MySQL Cluster to a release after the affected ranges listed above; the exact fixed version is unknown from the sources.","status":"open","published_at":"2026-10-20T22:18:34+00:00","first_seen_at":"2026-10-23T21:57:23+00:00","triaged_at":"2026-10-25T03:53:41+00:00","updated_at":"2026-10-25T03:53:41+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T03:53:41Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade MySQL Server or MySQL Cluster to a release after the affected ranges listed above; the exact fixed version is unknown from the sources.","reach":"network","title":"MySQL Server optimizer flaw lets low-privileged users crash the database","impact":"low","summary":"A flaw in the MySQL Server optimizer lets an attacker with low-privilege database access trigger a hang or repeatable crash. The result is a denial of service against MySQL Server and MySQL Cluster, with no data read or changed according to the CVSS vector.","category":"package","nicknames":[],"who_cares":["mysql","databases","self-hosted"],"confidence":0.7,"needs_auth":"yes","worst_case":"Database server hangs or crashes repeatedly, causing denial of service","analyst_note":"Confirm the fixed version for each affected branch in the Oracle MySQL security advisory (not in the sources given here).","how_to_check":"- Run `SELECT VERSION();` in MySQL and compare against the affected ranges: MySQL Server 8.4.0 to 8.4.12, 9.7.0 to 9.7.3, 26.7.0 to 26.7.1; MySQL Cluster 8.0.0 to 8.0.49, 8.4.0 to 8.4.12, 9.7.0 to 9.7.3, 26.7.0 to 26.7.1.","needs_analyst":true,"not_affected_if":["unaffected-version","no-untrusted-db-accounts"],"who_is_affected":"Any deployment running an affected MySQL Server or MySQL Cluster version where low-privileged accounts can reach the network listener. Systems on unaffected versions, or where only fully trusted administrators can connect, can skip it.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000676,"input_tokens":3585,"output_tokens":635,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-101789':15A,18A '-2026':14A,17A '/av':165C '26.7.0':97C,108C '26.7.1':98C,109C '3.1':155C,164C '6.5':158C '8.0.0':101C '8.0.49':102C '8.4.0':93C,103C '8.4.12':94C,104C '9.7.0':95C,105C '9.7.3':96C,106C 'abil':138C 'access':40B,119C 'accord':66B 'affect':89C 'allow':113C 'attack':34B,116C,130C 'avail':159C 'base':156C 'caus':140C 'chang':65B 'cluster':59B,77C,100C,128C,153C 'complet':147C 'compon':82C 'compromis':124C 'crash':10A,46B,146C 'cve':13A,16A 'cvss':69B,154C,161C,163C 'data':62B 'databas':12A,19B,39B 'denial':51B 'dos':148C 'easili':110C 'exploit':111C 'flaw':4A,26B 'frequent':144C 'h':173C 'hang':43B,142C 'host':24B 'impact':160C 'l/pr':167C 'l/ui':168C 'let':5A,32B 'low':7A,37B,114C 'low-privileg':6A,36B 'multipl':121C 'mysql':1A,20B,29B,55B,58B,74C,76C,81C,91C,99C,125C,127C,150C,152C 'n/a':172C 'n/ac':166C 'n/i':171C 'n/s':169C 'network':118C 'optim':3A,31B,84C 'oracl':80C 'packag':21B 'privileg':8A,38B,115C 'product':78C 'protocol':122C 'read':63B 'repeat':45B,145C 'result':48B,135C 'score':157C 'self':23B 'self-host':22B 'server':2A,30B,56B,75C,83C,92C,126C,151C 'servic':53B 'success':129C 'support':85C 'trigger':41B 'u/c':170C 'unauthor':137C 'user':9A 'vector':70B,162C 'version':86C 'via':120C 'vulner':71C,112C,133C","nicknames":[],"mitigations":[],"who_affected":"Any deployment running an affected MySQL Server or MySQL Cluster version where low-privileged accounts can reach the network listener. Systems on unaffected versions, or where only fully trusted administrators can connect, can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-20T22:18:34+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:L/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-2026-101789","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-101789","severity":null,"published_at":"2026-10-20T22:18:34+00:00","modified_at":"2026-10-22T18:17:23+00:00","first_seen_at":"2026-10-23T21:57:23+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"}