{"id":"CVE-2026-111816","kind":"vulnerability","aliases":["CVE-2026-111816"],"related":[],"title":"Apache Traffic Server: malformed 302 responses enable cache poisoning and desync","description":"Apache Traffic Server forwarded a malformed 302 response that should have been rejected as a parse error, because the Transfer-Encoding: chunked carve-out bypassed the rejection path. A response that two peers can read differently is then stored and served, allowing cache poisoning and response-framing desync.\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 accepts a malformed 302 response that uses chunked Transfer-Encoding when it should reject it. Peers can parse the same response differently, so an attacker can have a poisoned response stored in the cache and served to other users.","severity":"critical","cvss":9.3,"epss":0.00237,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["apache-traffic-server","caching-proxy","runtime","self-hosted"],"not_affected_if":["managed-hosting"],"how_to_check":"Check the installed version with traffic_server --version or the package manager; affected are 8.0.0 through 8.1.11, 9.0.0 through 9.2.15, 10.0.0 through 10.1.4, and 10.2.0.","fix":"Upgrade to 9.2.16, 10.1.5, or 10.2.1, matching your release line.","status":"open","published_at":"2026-10-21T19:16:59+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-23T22:32:55+00:00","updated_at":"2026-10-24T13:15:54+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-23T22:32:55Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade to 9.2.16, 10.1.5, or 10.2.1, matching your release line.\nunknown","reach":"internet","title":"Apache Traffic Server: malformed 302 responses enable cache poisoning and desync","impact":"high","summary":"Apache Traffic Server accepts a malformed 302 response that uses chunked Transfer-Encoding when it should reject it. Peers can parse the same response differently, so an attacker can have a poisoned response stored in the cache and served to other users.","category":"runtime","who_cares":["apache-traffic-server","caching-proxy","self-hosted"],"confidence":0.7,"needs_auth":"no","worst_case":"attacker poisons cache and desyncs responses for other users","analyst_note":"Confirm the affected version ranges and whether a default config is exploitable, using the NVD entry and the Apache Traffic Server security advisory.","how_to_check":"Check the installed version with traffic_server --version or the package manager; affected are 8.0.0 through 8.1.11, 9.0.0 through 9.2.15, 10.0.0 through 10.1.4, and 10.2.0.\nunknown","needs_analyst":true,"not_affected_if":["managed-hosting"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000536,"input_tokens":3045,"output_tokens":463,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-111816':14A,17A '-2026':13A,16A '10.0.0':138C '10.1.4':140C '10.1.5':150C '10.2.0':141C '10.2.1':152C '302':5A,35B,78C '8.0.0':130C '8.1.11':132C '9.0.0':134C '9.2.15':136C '9.2.16':149C 'accept':32B 'affect':125C 'allow':115C 'apach':1A,19B,29B,72C,126C 'apache-traffic-serv':18B 'attack':57B 'bypass':98C 'cach':8A,23B,66B,116C 'caching-proxi':22B 'carv':96C 'carve-out':95C 'chunk':39B,94C 'cve':12A,15A 'desync':11A,122C 'differ':54B,109C 'enabl':7A 'encod':42B,93C 'error':88C 'fix':154C 'forward':75C 'frame':121C 'host':28B 'issu':124C,156C 'malform':4A,34B,77C 'pars':50B,87C 'path':101C 'peer':48B,106C 'poison':9A,61B,117C 'proxi':24B 'read':108C 'recommend':144C 'reject':46B,84C,100C 'respons':6A,36B,53B,62B,79C,103C,120C 'response-fram':119C 'runtim':25B 'self':27B 'self-host':26B 'serv':68B,114C 'server':3A,21B,31B,74C,128C 'store':63B,112C 'traffic':2A,20B,30B,73C,127C 'transfer':41B,92C 'transfer-encod':40B,91C 'two':105C 'upgrad':146C 'use':38B 'user':71B,142C 'version':148C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T19:16:59+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/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-2026-111816","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111816","severity":null,"published_at":"2026-10-21T19:16:59+00:00","modified_at":"2026-10-23T22:16:55+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-2026-111816","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-111816","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"}