{"id":"CVE-2026-80212","details":"An issue was discovered in the resolv gem before 0.7.2 for Ruby. Resolv::DNS::Resource.get_class, Resolv::DNS::Resource::Generic.create, and Resolv::DNS::SvcParam::Generic.create generate a new class for each unknown DNS resource record (type, class) pair, or each unknown SvcParamKey, encountered while decoding a response. Each generated class was permanently registered both as a constant on Resource (or SvcParam::Generic) and as an entry in a class-lookup hash (ClassHash), and thus the class remained reachable through that constant after the response was discarded. Type and class are each 16-bit values, and thus an attacker controlling DNS responses (a spoofed response, or a malicious or hijacked upstream DNS server) has roughly 2^32 distinct (type, class) pairs to choose from. A single response of a few hundred kilobytes carrying tens of thousands of distinct unknown types permanently grows process memory by tens of megabytes; repeated responses accumulate without bound and are never reclaimed by garbage collection, because the constant keeps each class alive. Any code path that calls Resolv::DNS::Message.decode on attacker-influenced DNS responses is affected. resolv is a default gem, and thus this is reachable from a plain Ruby installation without any additional dependency.","modified":"2026-08-29T03:30:33.823464900Z","published":"2026-08-27T14:15:04.403Z","database_specific":{"cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80212.json","cna_assigner":"mitre"},"references":[{"type":"WEB","url":"https://www.ruby-lang.org/en/news/2026/08/27/multiple-vulnerabilities-in-resolv/"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80212.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80212"},{"type":"PACKAGE","url":"https://github.com/ruby/resolv"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/ruby/resolv","events":[{"introduced":"0"},{"fixed":"449683782b1c657d7217e36cd027013c30ca83d8"},{"introduced":"44ae1e8531e6986a329c4e6800c2ef95dbfc25f0"},{"fixed":"5e7205c7a84f6fd000349ced8f97550511bf1b1d"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"0.3.2"},{"introduced":"0.4.0"},{"fixed":"0.7.2"}],"source":"AFFECTED_FIELD"}}],"versions":["v0.3.1","v0.7.1","v0.7.0","v0.6.3","v0.6.2","v0.2.2","v0.3.0","v0.6.1","v0.6.0","v0.5.0","v0.4.0","v0.2.1","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80212.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}