{"affected":[{"package":{"ecosystem":"Hex","name":"safeurl","purl":"pkg:hex/safeurl"},"ranges":[{"events":[{"introduced":"0.1.0"}],"type":"SEMVER"}],"versions":["0.1.0","0.2.0","0.3.0","0.3.1","1.0.0"]},{"ranges":[{"events":[{"introduced":"feabbd0a13f83028ab24b71710526e9da9841f70"}],"repo":"https://github.com/slab/safeurl-elixir","type":"GIT"}]}],"aliases":["CVE-2026-77972"],"credits":[{"name":"Jonatan Männchen / EEF","type":"REPORTER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}],"database_specific":{"capec_ids":["CAPEC-664"],"cpe_ids":["cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-367"]},"details":"## Summary\n\nTime-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname's DNS responses to reach internal network destinations that validation rejected.\n\nValidation returns a verdict and not the address it approved, so the HTTP clients the library ships receive the original hostname and resolve it a second time when the request is made. An attacker who controls the authoritative DNS for a name can answer the first lookup with a permitted address and the second with a blocked one, and the request then reaches a destination validation never approved. The same window opens without an attacker whenever a name legitimately resolves to different addresses across lookups, such as short record lifetimes or rotation between several addresses.\n\nThis issue affects safeurl: from 0.1.0 onward.","id":"EEF-CVE-2026-77972","modified":"2026-09-15T15:37:50.506106Z","published":"2026-09-15T15:37:49.948Z","references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-77972.html"},{"type":"WEB","url":"https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70"},{"type":"PACKAGE","url":"https://hex.pm/packages/safeurl"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N","type":"CVSS_V4"}],"summary":"safeurl validated address is not bound to the request, allowing DNS rebinding","upstream":[]}