{"id":"CVE-2026-32688","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-32688","generatedAt":"2026-10-28T04:36:44.344Z","title":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion.","description":"Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion.\n\nPlug.Cowboy.Conn.conn/1 in lib/plug/cowboy/conn.ex calls String.to_atom/1 on the value returned by :cowboy_req.scheme/1. For HTTP/2 connections, cowlib passes the client-supplied :scheme pseudo-header value through verbatim without validation. Each unique value permanently allocates a new entry in the BEAM atom table. Since atoms are never garbage-collected and the atom table has a fixed limit (default 1,048,576), an unauthenticated attacker can exhaust the table by sending HTTP/2 requests with unique :scheme values, causing the Erlang VM to abort with system_limit and taking down the entire node.\n\nThis vulnerability does not affect HTTP/1.1, where cowboy derives the scheme from the listener type rather than from a client-supplied header.\n\nThis issue affects plug_cowboy: from 2.0.0 before 2.8.1.","published":"2026-04-27T14:16:47.000Z","lastModified":"2026-10-26T21:10:00.000Z","status":"Analyzed","sourceIdentifier":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","cvss":{"version":"4.0","score":8.7,"severity":"HIGH","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/M"},"cwe":["CWE-770"],"affected":["elixir-plug/plug.cowboy"],"epss":{"score":0.00545,"percentile":0.4556,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.55%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-32688.html","tags":["Third Party Advisory"],"source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/elixir-plug/plug_cowboy/commit/bfb34cb45eb354e56437f7023fb306de1bf9c19b","tags":["Patch"],"source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/elixir-plug/plug_cowboy/security/advisories/GHSA-q8x4-x7mp-5vg2","tags":["Vendor Advisory"],"source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-32688","tags":["Third Party Advisory"],"source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-32688","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}