{"id":"CVE-2026-108525","kind":"vulnerability","aliases":["CVE-2026-108525"],"related":[],"title":"Bandit: HTTP/2 flow-control gap lets remote clients exhaust server memory","description":"Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via DATA frames sent past the advertised receive window. The attacker requests a response larger than the 65,535-byte initial window and withholds WINDOW_UPDATE, so the stream process blocks while sending and stops reading, then floods small DATA frames on that stream. Every frame is queued in the stream's mailbox until the BEAM node runs out of memory.\n\nBandit.HTTP2.Connection.handle_frame/3 in lib/bandit/http2/connection.ex forwards each DATA frame to the stream process without consulting the receive window, and Bandit.HTTP2.FlowControl.compute_recv_window/2 replenishes the window as data arrives rather than as it is consumed, and never answers a violation with FLOW_CONTROL_ERROR.\n\nThis issue affects bandit: from 0.3.1 before 1.14.0.","summary":"Bandit, an Elixir HTTP server, does not enforce the HTTP/2 receive window, so a client can send DATA frames past the window and have them queued in memory. An unauthenticated remote attacker can exhaust server memory and crash the BEAM node.","severity":"high","cvss":8.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["bandit","elixir","http2","package","phoenix","self-hosted"],"not_affected_if":["bandit-1.14.0-or-later","no-http2-listener"],"how_to_check":"- Check the Bandit version in `mix.lock` or `mix deps` output; affected versions are from `0.3.1` before `1.14.0`.\n- Confirm HTTP/2 is served by Bandit, e.g. the endpoint is configured with `plug_cowboy` replaced by Bandit or `http: [protocol_options: [http_1: false]]` style settings the sources do not specify; unknown beyond the version check.","fix":"- Upgrade Bandit to `1.14.0` or later.\n- Redeploy the application and restart the BEAM node.","status":"open","published_at":"2026-10-26T14:16:24+00:00","first_seen_at":"2026-10-26T14:30:36+00:00","triaged_at":"2026-10-26T14:32:17+00:00","updated_at":"2026-10-26T14:32:17+00:00","category":"package","confidence":0.8,"triage":{"at":"2026-10-26T14:32:17Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Bandit to `1.14.0` or later.\n- Redeploy the application and restart the BEAM node.","reach":"internet","title":"Bandit: HTTP/2 flow-control gap lets remote clients exhaust server memory","impact":"medium","summary":"Bandit, an Elixir HTTP server, does not enforce the HTTP/2 receive window, so a client can send DATA frames past the window and have them queued in memory. An unauthenticated remote attacker can exhaust server memory and crash the BEAM node.","category":"package","nicknames":[],"who_cares":["elixir","phoenix","bandit","http2","self-hosted"],"confidence":0.8,"needs_auth":"no","worst_case":"Remote clients exhaust server memory and crash the BEAM node","analyst_note":"Check the NVD entry and the Bandit 1.14.0 release notes for whether HTTP/2 must be enabled and whether a proxy in front blocks the attack.","how_to_check":"- Check the Bandit version in `mix.lock` or `mix deps` output; affected versions are from `0.3.1` before `1.14.0`.\n- Confirm HTTP/2 is served by Bandit, e.g. the endpoint is configured with `plug_cowboy` replaced by Bandit or `http: [protocol_options: [http_1: false]]` style settings the sources do not specify; unknown beyond the version check.","needs_analyst":true,"not_affected_if":["bandit-1.14.0-or-later","no-http2-listener"],"who_is_affected":"Any Elixir application that serves HTTP/2 through Bandit at a version from `0.3.1` before `1.14.0` is exposed, because the flaw sits in the connection and flow-control code that accepts client requests. Systems that do not run Bandit, or that only serve HTTP/1.1 or sit behind a proxy that terminates HTTP/2, may not be reachable; the sources do not say which configurations are exposed beyond this.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000716,"input_tokens":3568,"output_tokens":718,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-108525':15A,18A '-2026':14A,17A '0.3.1':200C '1.14.0':202C '535':110C '65':109C 'advertis':98C 'affect':197C 'alloc':68C 'allow':83C 'answer':188C 'arriv':179C 'attack':58B,87C,102C 'bandit':1A,19B,27B,82C,198C 'bandit.http2.connection.handle':153C 'bandit.http2.flowcontrol.compute':171C 'beam':66B,147C 'block':122C 'byte':111C 'client':9A,41B 'consult':166C 'consum':185C 'control':5A,193C 'crash':64B 'cve':13A,16A 'data':44B,93C,131C,159C,178C 'elixir':20B,29B 'enforc':34B 'error':194C 'everi':136C 'exhaust':10A,60B,89C 'flood':129C 'flow':4A,192C 'flow-control':3A 'forward':157C 'frame':45B,94C,132C,137C,160C 'frame/3':154C 'gap':6A 'host':26B 'http':30B 'http/2':2A,36B,78C 'http2':21B 'implement':79C 'initi':112C 'issu':196C 'larger':106C 'let':7A 'lib/bandit/http2/connection.ex':156C 'limit':72C 'mailbox':144C 'memori':12A,54B,62B,91C,152C 'mtrudel':81C 'never':187C 'node':67B,148C 'packag':22B 'past':46B,96C 'phoenix':23B 'process':121C,164C 'queu':52B,139C 'rather':180C 'read':127C 'receiv':37B,99C,168C 'recv':172C 'remot':8A,57B,86C 'replenish':174C 'request':103C 'resourc':70C 'respons':105C 'run':149C 'self':25B 'self-host':24B 'send':43B,124C 'sent':95C 'server':11A,31B,61B,90C 'small':130C 'stop':126C 'stream':120C,135C,142C,163C 'throttl':74C 'unauthent':56B,85C 'updat':117C 'via':92C 'violat':190C 'vulner':75C 'window':38B,48B,100C,113C,116C,169C,176C 'window/2':173C 'withhold':115C 'without':71C,165C","nicknames":[],"mitigations":[],"who_affected":"Any Elixir application that serves HTTP/2 through Bandit at a version from `0.3.1` before `1.14.0` is exposed, because the flaw sits in the connection and flow-control code that accepts client requests. Systems that do not run Bandit, or that only serve HTTP/1.1 or sit behind a proxy that terminates HTTP/2, may not be reachable; the sources do not say which configurations are exposed beyond this.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-26T14:16:24+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-108525","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-108525","severity":null,"published_at":"2026-10-26T14:16:24+00:00","modified_at":"2026-10-26T14:16:24+00:00","first_seen_at":"2026-10-26T14:30:36+00:00","fetched_at":"2026-10-26T14:30:36+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"}