{"id":"UBUNTU-CVE-2026-109821","details":"Improper Validation of Specified Quantity in Input vulnerability in the Elixir standard library's URI module allows an attacker who supplies a URL to cause a denial of service through CPU exhaustion. URI.parse/1 converts the port component with String.to_integer/1 in split_authority/1 (lib/elixir/lib/uri.ex) without bounding its length, so a port of up to 1,262,592 decimal digits produces a bignum of that size and a longer one raises SystemLimitError. Rendering the parsed URI back to text (URI.to_string/1, inspect/1, logging, error formatting) converts the bignum with :erlang.integer_to_binary/1, which is quadratic on Erlang/OTP 27, 28 and 29.0: a 400,000-digit port renders in about 2.6 seconds and a 1 MB port in about 18 seconds. Ports above 65535 are also accepted. This issue affects elixir: from 0.5.0 before 1.18.6, from 1.19.0-rc.0 before 1.19.7, and from 1.20.0-rc.0 before 1.20.5.","modified":"2026-10-31T03:30:04.453012125Z","published":"2026-10-30T00:00:00Z","upstream":["CVE-2026-109821"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-109821"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-109821"},{"type":"REPORT","url":"https://cna.erlef.org/cves/CVE-2026-109821.html"},{"type":"REPORT","url":"https://github.com/elixir-lang/elixir/commit/07d9abc3f3ac4c8d2ba8384bd102b6d6205b08b7"},{"type":"REPORT","url":"https://github.com/elixir-lang/elixir/commit/39801821eef2d06524e5ebf5a0e4b3c380ad23ae"},{"type":"REPORT","url":"https://github.com/elixir-lang/elixir/commit/9a39d64a4473d02681c486bc70681c972479d32b"},{"type":"REPORT","url":"https://github.com/elixir-lang/elixir/commit/b70f33a591b6ab8eb0fa4a7e00bac1c2ed4e0d58"},{"type":"REPORT","url":"https://github.com/elixir-lang/elixir/commit/d879b39d778fec2f475689573d5672720c4f2a21"},{"type":"REPORT","url":"https://github.com/elixir-lang/elixir/security/advisories/GHSA-327h-97cv-59xg"},{"type":"REPORT","url":"https://github.com/erlang/otp/security/advisories/GHSA-8qw4-2chm-mvj2"},{"type":"REPORT","url":"https://osv.dev/vulnerability/EEF-CVE-2026-109821"}],"affected":[{"package":{"name":"elixir","ecosystem":"Ubuntu:14.04:LTS","purl":"pkg:deb/ubuntu/elixir?arch=source&distro=trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.7.1-1","0.7.1-2","0.7.1-4build0.14.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"python-elixir","binary_version":"0.7.1-4build0.14.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109821.json"}},{"package":{"name":"elixir","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/elixir?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.7.1-3","0.7.1-4build0.16.04.1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.7.1-4build0.16.04.1","binary_name":"python-elixir"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109821.json"}},{"package":{"name":"elixir","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/elixir?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.7.1-4build1"],"ecosystem_specific":{"binaries":[{"binary_name":"python-elixir","binary_version":"0.7.1-4build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109821.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}