{"id":"CVE-2026-91403","kind":"vulnerability","aliases":["CVE-2026-91403"],"related":[],"title":"Java SE JSSE: unauthenticated network flaw exposes critical data","description":"Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: JSSE).  Supported versions that are affected are Oracle Java SE: 8u511, 8u511-perf, 11.0.33, 17.0.21, 21.0.13, 25.0.5, 27.0.1; Oracle GraalVM for JDK: 17.0.21 and  21.0.13; Oracle GraalVM Enterprise Edition: 21.3.20. Easily exploitable vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition.  Successful attacks of this vulnerability can result in  unauthorized creation, deletion or modification access to critical data or all Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data as well as  unauthorized access to critical data or complete access to all Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition accessible data. Note: This vulnerability can be exploited by using APIs in the specified Component, e.g., through a web service which supplies data to the APIs. This vulnerability also applies to Java deployments, typically in clients running sandboxed Java Web Start applications or sandboxed Java applets, that load and run untrusted code (e.g., code that comes from the internet) and rely on the Java sandbox for security. CVSS 3.1 Base Score 9.1 (Confidentiality and Integrity impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N).","summary":"A flaw in the JSSE (TLS) component of Oracle Java SE and GraalVM lets a remote attacker with no account change or read data the software handles. It is reachable over multiple network protocols through services that pass data to the affected APIs.","severity":"critical","cvss":9.1,"epss":0.00392,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["graalvm","java","jvm","network-services","poc-public","runtime","self-hosted"],"not_affected_if":["default-config"],"how_to_check":"java -version\nCompare the version against the affected list: Java SE 8u511, 11.0.33, 17.0.21, 21.0.13, 25.0.5, 27.0.1; GraalVM for JDK 17.0.21 and 21.0.13; GraalVM Enterprise 21.3.20.","fix":"Upgrade to a patched Oracle Java SE or GraalVM release from the vendor's April 2026 Critical Patch Update; the sources do not list the exact fixed build numbers.","status":"open","published_at":"2026-10-21T22:16:50+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-23T22:32:47+00:00","updated_at":"2026-10-24T13:15:54+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-23T22:32:47Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade to a patched Oracle Java SE or GraalVM release from the vendor's April 2026 Critical Patch Update; the sources do not list the exact fixed build numbers.\nUnknown: the sources do not name a fixed build for each line.","reach":"internet","title":"Java SE JSSE: unauthenticated network flaw exposes critical data","impact":"high","summary":"A flaw in the JSSE (TLS) component of Oracle Java SE and GraalVM lets a remote attacker with no account change or read data the software handles. It is reachable over multiple network protocols through services that pass data to the affected APIs.","category":"runtime","who_cares":["java","jvm","graalvm","self-hosted","network-services"],"confidence":0.7,"needs_auth":"no","worst_case":"Remote attacker modifies or deletes critical data without credentials","analyst_note":"Confirm fixed build numbers per Java line and whether a specific JSSE API or protocol (TLS) is the trigger, via the Oracle Critical Patch Update advisory linked from NVD.","how_to_check":"java -version\nCompare the version against the affected list: Java SE 8u511, 11.0.33, 17.0.21, 21.0.13, 25.0.5, 27.0.1; GraalVM for JDK 17.0.21 and 21.0.13; GraalVM Enterprise 21.3.20.","needs_analyst":true,"not_affected_if":["default-config"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000617,"input_tokens":3477,"output_tokens":539,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-2026':11A,14A '-91403':12A,15A '/av':284C '11.0.33':106C '17.0.21':107C,115C '21.0.13':108C,117C '21.3.20':122C '25.0.5':109C '27.0.1':110C '3.1':272C,283C '8u511':102C,104C '8u511-perf':103C '9.1':275C 'access':131C,161C,178C,184C,190C,204C 'account':48B 'affect':70B,97C 'allow':126C 'also':232C 'api':71B,214C,229C 'applet':249C 'appli':233C 'applic':245C 'attack':45B,128C,149C 'base':273C 'chang':49B 'client':239C 'code':255C,257C 'come':259C 'complet':189C 'compon':35B,91C,218C 'compromis':136C 'confidenti':276C 'creation':157C 'critic':8A,163C,186C 'cve':10A,13A 'cvss':271C,280C,282C 'data':9A,52B,67B,164C,179C,187C,205C,226C 'delet':158C 'deploy':236C 'e.g':219C,256C 'easili':123C 'edit':85C,121C,147C,177C,203C 'enterpris':84C,120C,146C,176C,202C 'exploit':124C,211C 'expos':7A 'flaw':6A,30B 'graalvm':16B,41B,79C,83C,112C,119C,141C,145C,171C,175C,197C,201C 'h/a':291C 'h/i':290C 'handl':55B 'host':28B 'impact':279C 'integr':278C 'internet':262C 'java':1A,17B,38B,76C,89C,100C,138C,168C,194C,235C,242C,248C,267C 'jdk':81C,114C,143C,173C,199C 'jsse':3A,33B,92C 'jvm':18B 'l/pr':286C 'let':42B 'load':251C 'modif':160C 'multipl':60B,133C 'n':292C 'n/ac':285C 'n/s':288C 'n/ui':287C 'network':5A,20B,61B,130C 'network-servic':19B 'note':206C 'oracl':37B,75C,78C,82C,88C,99C,111C,118C,137C,140C,144C,167C,170C,174C,193C,196C,200C 'pass':66B 'perf':105C 'poc':23B 'poc-publ':22B 'product':86C 'protocol':62B,134C 'public':24B 'reachabl':58B 'read':51B 'reli':264C 'remot':44B 'result':154C 'run':240C,253C 'runtim':25B 'sandbox':241C,247C,268C 'score':274C 'se':2A,39B,77C,90C,101C,139C,169C,195C 'secur':270C 'self':27B 'self-host':26B 'servic':21B,64B,223C 'softwar':54B 'specifi':217C 'start':244C 'success':148C 'suppli':225C 'support':93C 'tls':34B 'typic':237C 'u/c':289C 'unauthent':4A,127C 'unauthor':156C,183C 'untrust':254C 'use':213C 'vector':281C 'version':94C 'via':132C 'vulner':72C,125C,152C,208C,231C 'web':222C,243C 'well':181C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T22:16:50+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","cvss_by":"secalert_us@oracle.com","poc_count":1,"sources":[{"source":"nvd","external_id":"CVE-2026-91403","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91403","severity":null,"published_at":"2026-10-21T22:16:50+00:00","modified_at":"2026-10-23T12:18:17+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"github-poc","external_id":"siladu/fix-cve-2026-91403","url":"https://github.com/siladu/fix-cve-2026-91403","severity":null,"published_at":"2026-10-24T01:19:32+00:00","modified_at":null,"first_seen_at":"2026-10-24T01:30:40+00:00","fetched_at":"2026-10-24T01:30:40+00:00","note":null},{"source":"epss","external_id":"CVE-2026-91403","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-91403","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T13:15:54+00:00","fetched_at":"2026-10-24T13:15:54+00:00","note":null}],"documents":[{"id":671,"url":"https://news.ycombinator.com/item?id=50188443","title":"Oracle Security Alert Advisory – CVE-2026-91403 (eMudhra cert revocation)","kind":"post","source":"hackernews","text":"Oracle Security Alert Advisory – CVE-2026-91403 (eMudhra cert revocation)\nhttps://www.oracle.com/security-alerts/alert-cve-2026-91403.html\n\n26 points, 3 comments on Hacker News","published_at":"2026-10-21T22:17:19+00:00","relation":"discussion","confidence":null,"note":null},{"id":2661,"url":"https://github.com/siladu/fix-cve-2026-91403","title":"siladu/fix-cve-2026-91403","kind":"poc","source":"github","text":"\n\nstars 0","published_at":"2026-10-24T01:19:32+00:00","relation":"poc","confidence":null,"note":"0 stars"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}