{"id":"CVE-2026-111817","kind":"vulnerability","aliases":["CVE-2026-111817"],"related":[],"title":"Apache Traffic Server: dropped chunked trailers can stall proxied transfers until timeout","description":"Apache Traffic Server can stall a chunked transfer that it passes through with its trailers removed (proxy.config.http.drop_chunked_trailers) until the connection times out, because it waits for the trailer bytes it has already dropped. Trailer dropping is on by default in 10.x. In 8.1.11 and 9.2.x it is off by default, and those versions are affected only if it is enabled.\n\n\n\nThis issue affects Apache Traffic Server: 8.1.11, from 9.2.5 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 10.1.5 or 10.2.1, which fix the issue.","summary":"Apache Traffic Server waits for trailer bytes it has already removed from a chunked transfer, so the response stalls until the connection times out. An attacker who can send such traffic can tie up connections and degrade availability; the sources do not describe code execution or data exposure.","severity":"medium","cvss":6.9,"epss":0.00262,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["apache-traffic-server","reverse-proxy","runtime","self-hosted"],"not_affected_if":["default-config","not-proxying-chunked-traffic"],"how_to_check":"- Check the Traffic Server version with `traffic_server -V` or the installed package version.\n- Check whether `proxy.config.http.drop_chunked_trailers` is enabled in `records.yaml` or `records.config`; on 10.x it is on by default.","fix":"- Upgrade Apache Traffic Server 10.x installs to `10.1.5` or `10.2.1`.\n- Upgrade 9.2.x installs in the affected range (`9.2.5` through `9.2.15`) to a fixed release; the sources do not name the fixed 9.2 version.\n- On 8.1.11 or 9.2.x, disable `proxy.config.http.drop_chunked_trailers` if upgrading is not possible.","status":"open","published_at":"2026-10-21T20:17:23+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-25T03:38:58+00:00","updated_at":"2026-10-25T03:38:58+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-25T03:38:58Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Apache Traffic Server 10.x installs to `10.1.5` or `10.2.1`.\n- Upgrade 9.2.x installs in the affected range (`9.2.5` through `9.2.15`) to a fixed release; the sources do not name the fixed 9.2 version.\n- On 8.1.11 or 9.2.x, disable `proxy.config.http.drop_chunked_trailers` if upgrading is not possible.","reach":"network","title":"Apache Traffic Server: dropped chunked trailers can stall proxied transfers until timeout","impact":"low","summary":"Apache Traffic Server waits for trailer bytes it has already removed from a chunked transfer, so the response stalls until the connection times out. An attacker who can send such traffic can tie up connections and degrade availability; the sources do not describe code execution or data exposure.","category":"runtime","nicknames":[],"who_cares":["apache-traffic-server","self-hosted","reverse-proxy"],"confidence":0.7,"needs_auth":"unknown","worst_case":"Proxied chunked responses stall until connection timeout, degrading availability","analyst_note":"","how_to_check":"- Check the Traffic Server version with `traffic_server -V` or the installed package version.\n- Check whether `proxy.config.http.drop_chunked_trailers` is enabled in `records.yaml` or `records.config`; on 10.x it is on by default.","needs_analyst":false,"not_affected_if":["default-config","not-proxying-chunked-traffic"],"who_is_affected":"Only deployments that proxy chunked HTTP transfers through Apache Traffic Server are exposed. On 10.x the trailer dropping is on by default, so default installs in the affected 10.x range are exposed; on 8.1.11 and 9.2.x only when the trailer-dropping setting is turned on. Teams not running Traffic Server as a proxy can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000697,"input_tokens":3480,"output_tokens":698,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-111817':15A,18A '-2026':14A,17A '10':120C '10.0.0':154C '10.1.4':156C '10.1.5':165C '10.2.0':157C '10.2.1':167C '8.1.11':123C,148C '9.2':125C '9.2.15':152C '9.2.5':150C 'affect':136C,144C 'alreadi':39B,111C 'apach':1A,20B,30B,78C,145C 'apache-traffic-serv':19B 'attack':55B 'avail':67B 'byte':36B,108C 'chunk':5A,43B,84C,95C 'code':73B 'connect':51B,64B,99C 'cve':13A,16A 'data':76B 'default':118C,131C 'degrad':66B 'describ':72B 'drop':4A,112C,114C 'enabl':141C 'execut':74B 'exposur':77B 'fix':169C 'host':29B 'issu':143C,171C 'pass':88C 'proxi':9A,25B 'proxy.config.http.drop':94C 'recommend':160C 'remov':40B,93C 'respons':47B 'revers':24B 'reverse-proxi':23B 'runtim':26B 'self':28B 'self-host':27B 'send':58B 'server':3A,22B,32B,80C,147C 'sourc':69B 'stall':8A,48B,82C 'tie':62B 'time':52B,100C 'timeout':12A 'traffic':2A,21B,31B,60B,79C,146C 'trailer':6A,35B,92C,96C,107C,113C 'transfer':10A,44B,85C 'upgrad':162C 'user':158C 'version':134C,164C 'wait':33B,104C 'x':121C,126C","nicknames":[],"mitigations":[],"who_affected":"Only deployments that proxy chunked HTTP transfers through Apache Traffic Server are exposed. On 10.x the trailer dropping is on by default, so default installs in the affected 10.x range are exposed; on 8.1.11 and 9.2.x only when the trailer-dropping setting is turned on. Teams not running Traffic Server as a proxy can skip it.","tier":"C","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:L/SC:N/SI:N/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-2026-111817","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111817","severity":null,"published_at":"2026-10-21T20:17:23+00:00","modified_at":"2026-10-23T22:16:56+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-2026-111817","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-111817","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"}