{"id":"CVE-2026-101572","kind":"vulnerability","aliases":["CVE-2026-101572"],"related":[],"title":"Helidon HTTP/2 client flaw lets unauthenticated attackers crash or hang services","description":"Vulnerability in the Helidon product of Oracle Fusion Middleware (component: helidon-webclient-http2).  Supported versions that are affected are 4.0.0-4.5.5 and 27.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP/2 to compromise Helidon.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Helidon. CVSS 3.1 Base Score 7.5 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).","summary":"Helidon's HTTP/2 web client component has a flaw that an unauthenticated attacker on the network can trigger over HTTP/2. Successful exploitation hangs or repeatedly crashes the Helidon application, a denial of service.","severity":"high","cvss":7.5,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"helidon-webclient-http2","fixed":[],"affected":">= 4.0.0, <= 4.5.5; 27.0.0","ecosystem":"maven"}],"ecosystems":[],"tags":["denial-of-service","helidon","http2","java","oracle-fusion-middleware","package","webclient"],"not_affected_if":["helidon-3.x","no-http2-webclient","unaffected-version"],"how_to_check":"Look for io.helidon.webclient:helidon-webclient-http2 (directly or through helidon-webclient) at 4.0.0-4.5.5 or 27.0.0: run mvn dependency:tree or gradle dependencies and grep helidon-webclient-http2. Only apps that use Helidon's HTTP/2 WebClient are in scope.","fix":"Likely upgrade to Helidon 4.5.6 (4.x line) or 27.0.1 (27.x line); not confirmed against Oracle's Helidon risk matrix row. Check the CPU October 2026 advisory (Fusion Middleware, Helidon) before relying on it.","status":"open","published_at":"2026-10-20T22:18:10+00:00","first_seen_at":"2026-10-23T21:57:22+00:00","triaged_at":"2026-10-25T03:20:16+00:00","updated_at":"2026-10-25T03:26:04+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-25T03:20:16Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Helidon HTTP/2 client flaw lets unauthenticated attackers crash or hang services","impact":"low","summary":"Helidon's HTTP/2 web client component has a flaw that an unauthenticated attacker on the network can trigger over HTTP/2. Successful exploitation hangs or repeatedly crashes the Helidon application, a denial of service.","category":"package","nicknames":[],"who_cares":["helidon","java","oracle-fusion-middleware"],"confidence":0.6,"needs_auth":"no","worst_case":"Service hangs or repeatedly crashes, causing denial of service","analyst_note":"Confirm the exact affected-version range and the fixed release in the NVD entry or Oracle's advisory, and whether the HTTP/2 client (not just server) is required to be exposed.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["unaffected-version"],"who_is_affected":"The sources list Helidon 4.0.0 through 4.5.5 and 27.0.0 as affected, specifically the helidon-webclient-http2 component. Teams running those versions with the HTTP/2 client in use should look closer. Teams on other versions can skip it on this evidence.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000582,"input_tokens":3468,"output_tokens":470,"severity_before":"high"},"analyst_status":"done","analyst_note":"Confirm the exact affected-version range and the fixed release in the NVD entry or Oracle's advisory, and whether the HTTP/2 client (not just server) is required to be exposed.","search":"'-101572':14A,17A '-2026':13A,16A '/av':139C '27.0.0':91C '3.1':129C,138C '4.0.0':88C '4.5.5':89C '7.5':132C 'abil':115C 'access':100C 'affect':86C 'allow':95C 'applic':63B 'attack':7A,47B,97C,107C 'avail':133C 'base':130C 'caus':117C 'client':3A,39B 'complet':124C 'compon':40B,77C 'compromis':104C 'crash':8A,60B,123C 'cve':12A,15A 'cvss':128C,135C,137C 'denial':23B,65B 'denial-of-servic':22B 'dos':125C 'easili':92C 'exploit':56B,93C 'flaw':4A,43B 'frequent':121C 'fusion':31B,75C 'h':147C 'hang':10A,57B,119C 'helidon':1A,19A,26B,35B,62B,71C,79C,105C,127C 'helidon-webclient-http2':18A,78C 'http/2':2A,37B,54B,102C 'http2':21A,27B,81C 'impact':134C 'java':28B 'l/pr':141C 'let':5A 'middlewar':32B,76C 'n/a':146C 'n/ac':140C 'n/i':145C 'n/s':143C 'n/ui':142C 'network':50B,99C 'oracl':30B,74C 'oracle-fusion-middlewar':29B 'packag':33B 'product':72C 'repeat':59B,122C 'result':112C 'score':131C 'servic':11A,25B,67B 'success':55B,106C 'support':82C 'trigger':52B 'u/c':144C 'unauthent':6A,46B,96C 'unauthor':114C 'vector':136C 'version':83C 'via':101C 'vulner':68C,94C,110C 'web':38B 'webclient':20A,34B,80C","nicknames":[],"mitigations":[],"who_affected":"The sources list Helidon 4.0.0 through 4.5.5 and 27.0.0 as affected, specifically the helidon-webclient-http2 component. Teams running those versions with the HTTP/2 client in use should look closer. Teams on other versions can skip it on this evidence.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-20T22:18:10+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/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-2026-101572","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-101572","severity":null,"published_at":"2026-10-20T22:18:10+00:00","modified_at":"2026-10-22T19:17:34+00:00","first_seen_at":"2026-10-23T21:57:22+00:00","fetched_at":"2026-10-23T22:28:58+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-101572:716","url":null,"severity":null,"published_at":"2026-10-25T03:26:04+00:00","modified_at":"2026-10-25T03:26:04+00:00","first_seen_at":"2026-10-25T03:26:04+00:00","fetched_at":"2026-10-25T03:26:04+00:00","note":"Affected range 4.0.0-4.5.5 and 27.0.0 confirmed via CVE record (Oracle CNA). Oracle CPU Oct 2026 matrix section for Helidon not read (page truncated), so fixed version is unconfirmed; 4.5.6 (20 Oct) and 27.0.1 exist and likely fix it. No exploitation or PoC found. Not marked verified. Related Helidon HTTP/2 DoS CVEs: CVE-2026-83276 (webclient), CVE-2026-83280 (webserver), fixed in earlier range <=4.5.4."}],"documents":[{"id":1637,"url":"https://www.oracle.com/security-alerts/cpuoct2026.html","title":"Oracle Critical Patch Update Advisory - October 2026","kind":"advisory","source":"analyst","text":"Lists Oracle E-Business Suite, versions 12.2.3-12.2.15 as affected; patches via Patch Availability Document (MOS). Released 2026-10-20.","published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":3169,"url":"https://www.cve.org/CVERecord?id=CVE-2026-101572","title":"CVE Record: CVE-2026-101572","kind":"other","source":"analyst","text":null,"published_at":null,"relation":"describes","confidence":null,"note":null},{"id":3170,"url":"https://github.com/helidon-io/helidon/releases","title":"Helidon releases (4.5.6, 20 Oct 2026)","kind":"release","source":"analyst","text":null,"published_at":null,"relation":"fix","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}