{"id":"CVE-2026-111815","kind":"vulnerability","aliases":["CVE-2026-111815"],"related":[],"title":"Apache Traffic Server: TLS session resumption skips client certificate check across SNI hosts","description":"Apache Traffic Server can resume a TLS session across SNI virtual hosts without re-verifying a client certificate required by the resumed host's verify_client STRICT policy.\n\n\n\nThis issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0.\n\n\n\nUsers are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.","summary":"Apache Traffic Server can resume a TLS session on a virtual host that requires client certificates without checking the certificate again. An attacker who holds a session from a permissive host may reach a strict mTLS host without presenting a valid client certificate.","severity":"critical","cvss":10.0,"epss":0.00172,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["apache-traffic-server","mtls","runtime","self-hosted","tls"],"not_affected_if":["default-config","no-verify-client-strict"],"how_to_check":"Check the installed version with traffic_server --version and compare it to the affected ranges 8.0.0-8.1.11, 9.0.0-9.2.15, 10.0.0-10.1.4 and 10.2.0.\nIf you use verify_client STRICT in sni.yaml, you are in scope.","fix":"Upgrade to 9.2.16, 10.1.5, or 10.2.1, matching your release line.","status":"open","published_at":"2026-10-21T20:17:23+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-23T22:32:51+00:00","updated_at":"2026-10-24T13:15:54+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-23T22:32:51Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade to 9.2.16, 10.1.5, or 10.2.1, matching your release line.","reach":"network","title":"Apache Traffic Server: TLS session resumption skips client certificate check across SNI hosts","impact":"high","summary":"Apache Traffic Server can resume a TLS session on a virtual host that requires client certificates without checking the certificate again. An attacker who holds a session from a permissive host may reach a strict mTLS host without presenting a valid client certificate.","category":"runtime","who_cares":["apache-traffic-server","mtls","tls","self-hosted"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Client certificate requirement bypassed, letting unauthenticated clients reach protected mTLS virtual hosts","analyst_note":"Confirm the exact trigger conditions for session resumption and whether a prior session from another vhost is required; check the Apache security advisory for details.","how_to_check":"Check the installed version with traffic_server --version and compare it to the affected ranges 8.0.0-8.1.11, 9.0.0-9.2.15, 10.0.0-10.1.4 and 10.2.0.\nIf you use verify_client STRICT in sni.yaml, you are in scope.","needs_analyst":true,"not_affected_if":["default-config","no-verify-client-strict"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000552,"input_tokens":3008,"output_tokens":502,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-111815':16A,19A '-2026':15A,18A '10.0.0':117C '10.1.4':119C '10.1.5':129C '10.2.0':120C '10.2.1':131C '8.0.0':109C '8.1.11':111C '9.0.0':113C '9.2.15':115C '9.2.16':128C 'across':11A,81C 'affect':104C 'apach':1A,21B,30B,73C,105C 'apache-traffic-serv':20B 'attack':52B 'certif':9A,45B,49B,72B,91C 'check':10A,47B 'client':8A,44B,71B,90C,99C 'cve':14A,17A 'fix':133C 'hold':54B 'host':13A,28B,41B,60B,66B,84C,96C 'issu':103C,135C 'may':61B 'mtls':24B,65B 'permiss':59B 'polici':101C 'present':68B 're':87C 're-verifi':86C 'reach':62B 'recommend':123C 'requir':43B,92C 'resum':34B,77C,95C 'resumpt':6A 'runtim':25B 'self':27B 'self-host':26B 'server':3A,23B,32B,75C,107C 'session':5A,37B,56B,80C 'skip':7A 'sni':12A,82C 'strict':64B,100C 'tls':4A,29B,36B,79C 'traffic':2A,22B,31B,74C,106C 'upgrad':125C 'user':121C 'valid':70B 'verifi':88C,98C 'version':127C 'virtual':40B,83C 'without':46B,67B,85C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T20:17:23+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"security@apache.org","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-111815","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111815","severity":null,"published_at":"2026-10-21T20:17:23+00:00","modified_at":"2026-10-23T12:18:09+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-111815","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-111815","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":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}