{"cve":"CVE-2026-54892","nvd":{"published":"2026-06-23T13:16:43.167","modified":"2026-10-25T23:10:00.167","status":"Deferred","description":"Inefficient algorithmic complexity in Plug's nested-parameter decoder allows an unauthenticated remote attacker to cause denial of service. Plug.Conn.Query.decode/4 (and Plug.Conn.Query.decode_each/2) parse query strings and application/x-www-form-urlencoded request bodies. When a key contains many bracketed segments such as a[a][a][a]=1, the decoder walks the brackets and, for each of the N levels, performs a map operation keyed on an ever-growing binary prefix of the key, hashing the full byte range at each step. The total decode cost is therefore quadratic in the number of nesting levels.\n\nWith the default Plug.Parsers.URLENCODED body limit of 1,000,000 bytes, a single request can carry roughly 333,000 nesting levels and saturate a BEAM scheduler for minutes. A small number of concurrent requests can saturate all schedulers and render a Plug-based server unresponsive. No authentication or knowledge of application routes is required.\n\nThis vulnerability is associated with program files lib/plug/conn/query.ex and program routines Plug.Conn.Query.decode/4, Plug.Conn.Query.decode_each/2, Plug.Conn.Query.split_keys/6, Plug.Conn.Query.insert_keys/3, and Plug.Conn.Query.finalize_pointer/2.\n\nThis issue affects plug from 1.15.0 before 1.15.5, 1.16.4, 1.17.2, 1.18.3, and 1.19.3.","cvss_v4":{"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","score":8.7},"cvss_v3":null,"cwes":["CWE-407"],"references":["https://cna.erlef.org/cves/CVE-2026-54892.html","https://github.com/elixir-plug/plug/commit/9c5d37c440eaae92869eed7c014c47266744fadb","https://github.com/elixir-plug/plug/commit/a61124aa625d819a218fb07f90afbac8aa85eb0e","https://github.com/elixir-plug/plug/commit/c317d08fdcf96e17931f7419275b2b8c4bf3e951","https://github.com/elixir-plug/plug/commit/d4e5568392a4b29e545b91e12e87d6098f976145"],"products":[],"source":"nvd","synced_at":"2026-10-25T23:44:33.281319194+00:00"},"epss":{"cve":"CVE-2026-54892","score":0.00949,"percentile":0.60966,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}