{"id":"CVE-2026-111814","kind":"vulnerability","aliases":["CVE-2026-111814"],"related":[],"title":"Apache Traffic Server: pooled TLS sessions reused across different client certificates","description":"Apache Traffic Server's default outbound session-sharing policy can reuse a pooled TLS session authenticated with one client certificate for a transaction configured to present a different one.\n\n\n\nThis issue affects Apache Traffic Server: 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's default outbound session-sharing policy can reuse a pooled TLS session that was authenticated with one client certificate for a transaction meant to present a different certificate. An attacker can therefore reach upstream servers under another client's identity.","severity":"critical","cvss":10.0,"epss":0.00172,"exploited":false,"exploited_at":null,"products":[{"name":"Apache Traffic Server","fixed":["9.2.16","10.1.5","10.2.1"],"affected":">= 9.0.0, <= 9.2.15; >= 10.0.0, <= 10.1.4; 10.2.0","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["apache-traffic-server","client-certificates","infrastructure","mtls","outbound-tls","reverse-proxy","self-hosted"],"not_affected_if":["no-origin-client-certs","no-outbound-client-certificates","not-using-ats"],"how_to_check":"Run traffic_server -V to get the version. Exposed if it is 9.0.0-9.2.15, 10.0.0-10.1.4 or 10.2.0 AND ATS makes TLS connections to origins that need client certificates (mTLS), with different certificates for different transactions or remaps. Check proxy.config.http.server_session_sharing.match in records.yaml or records.config. The default omits the certificate mask (MASK_CERT), so the default is affected. If you never present client certificates to origins, you are not exposed.","fix":"Upgrade to 9.2.16, 10.1.5 or 10.2.1. The advisory names no workaround; unverified suggestion: set server_session_sharing.match so it includes the cert mask, or turn off origin session sharing.","status":"open","published_at":"2026-10-21T20:17:23+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-23T22:32:50+00:00","updated_at":"2026-10-24T13:15:54+00:00","category":"infrastructure","confidence":0.8,"triage":{"at":"2026-10-23T22:32:50Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade Apache Traffic Server to 9.2.16, 10.1.5, or 10.2.1 (9.0.0 through 9.2.15, 10.0.0 through 10.1.4, and 10.2.0 are affected).","reach":"network","title":"Apache Traffic Server: pooled TLS sessions reused across different client certificates","impact":"high","summary":"Apache Traffic Server's default outbound session-sharing policy can reuse a pooled TLS session that was authenticated with one client certificate for a transaction meant to present a different certificate. An attacker can therefore reach upstream servers under another client's identity.","category":"infrastructure","who_cares":["apache-traffic-server","outbound-tls","client-certificates"],"confidence":0.6,"needs_auth":"unknown","worst_case":"requests reach upstream servers under another client's certificate identity","analyst_note":"Check the NVD entry and the Apache advisory for the default session-sharing setting and the exact config that presents client certificates to confirm how_to_check.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-outbound-client-certificates"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000517,"input_tokens":2993,"output_tokens":435,"severity_before":"critical"},"analyst_status":"done","analyst_note":"Check the NVD entry and the Apache advisory for the default session-sharing setting and the exact config that presents client certificates to confirm how_to_check.","search":"'-111814':14A,17A '-2026':13A,16A '10.0.0':124C '10.1.4':126C '10.1.5':136C '10.2.0':127C '10.2.1':138C '9.0.0':120C '9.2.15':122C '9.2.16':135C 'across':8A 'affect':115C 'anoth':79B 'apach':1A,22B,39B,83C,116C 'apache':18A 'apache-traffic-serv':21B 'attack':72B 'authent':57B,99C 'certif':11A,27B,61B,70B,103C 'client':10A,26B,60B,80B,102C 'client-certif':25B 'configur':107C 'cve':12A,15A 'default':43B,87C 'differ':9A,69B,111C 'fix':140C 'host':38B 'ident':82B 'infrastructur':28B 'issu':114C,142C 'meant':65B 'mtls':29B 'one':59B,101C,112C 'outbound':31B,44B,88C 'outbound-tl':30B 'polici':48B,92C 'pool':4A,52B,96C 'present':67B,109C 'proxi':35B 'reach':75B 'recommend':130C 'reus':7A,50B,94C 'revers':34B 'reverse-proxi':33B 'self':37B 'self-host':36B 'server':3A,20A,24B,41B,77B,85C,118C 'session':6A,46B,54B,90C,98C 'session-shar':45B,89C 'share':47B,91C 'therefor':74B 'tls':5A,32B,53B,97C 'traffic':2A,19A,23B,40B,84C,117C 'transact':64B,106C 'upgrad':132C 'upstream':76B 'user':128C 'version':134C","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:L/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-2026-111814","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111814","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":"analyst","external_id":"CVE-2026-111814:308","url":null,"severity":null,"published_at":"2026-10-23T22:49:43+00:00","modified_at":"2026-10-23T22:49:43+00:00","first_seen_at":"2026-10-23T22:49:43+00:00","fetched_at":"2026-10-23T22:49:43+00:00","note":"Read Apache ATS Oct 2026 advisory (primary): default server_session_sharing.match omits MASK_CERT; fixed 9.2.16/10.1.5/10.2.1; reporter Craig Taylor. Apache rates Important; CVSS 3.1 is 10.0, v4.0 is 7.8. No exploitation or PoC reported (StackRef bulletin). No social posts searched. Advisory gives no config snippet; how_to_check is inferred from the setting name."},{"source":"epss","external_id":"CVE-2026-111814","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-111814","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":1624,"url":"https://trafficserver.apache.org/security-2026-10.html","title":"Apache Traffic Server October 2026 CVE Release","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":1625,"url":"https://whistle.stackref.com/post/2026-10-22-cve-bulletin-ats-traefik-trust/","title":"The Whistle: mTLS bypasses in Traffic Server and Traefik","kind":"blog","source":"analyst","text":null,"published_at":null,"relation":"mentions","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"}