{"id":"CVE-2026-77972","aliases":["EEF-CVE-2026-77972","EUVD-2026-78676","GHSA-pqwh-q74p-w7h4"],"status":"published","title":"safeurl validated address is not bound to the request, allowing DNS rebinding","description":"Time-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.","severity":{"version":"4.0","score":9,"vector":"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","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00331,"percentile":0.26466,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-367"],"published":"2026-09-15T15:37:49Z","modified":"2026-10-28T02:31:02Z","affected":[{"source":"osv","ecosystem":"Hex","package":"safeurl","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"}]}],"versions":["0.1.0","0.2.0","0.3.0","0.3.1","1.0.0"]}],"products":[{"vendor":"doyensec","product":"safeurl"},{"vendor":"slab","product":"safeurl"}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-77972.html","tags":["related","third-party-advisory","advisory","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-77972","tags":["related","web"]},{"url":"https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70","tags":["related","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77972","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-pqwh-q74p-w7h4"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77972.json","tags":["advisory"]},{"url":"https://github.com/slab/safeurl-elixir","tags":["package"]},{"url":"https://hex.pm/packages/safeurl","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-77972","title":"safeurl validated address is not bound to the request, allowing DNS rebinding","description":"Time-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.","status":"published","published":"2026-09-15T15:37:49.948Z","modified":"2026-09-21T18:44:16.787Z","cvss":[{"version":"4.0","score":9,"vector":"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","level":"critical","assessor":"cna"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T14:20:15.712761Z"}],"euvd":[{"id":"EUVD-2026-78676","description":"Time-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.","status":"published","published":"2026-09-15T15:37:49Z","modified":"2026-09-21T18:44:16Z","cvss":[{"version":"4.0","score":9,"vector":"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","level":"critical"}],"updated_at":"2026-11-02T17:28:04.588371Z"}],"ghsa":[{"id":"GHSA-pqwh-q74p-w7h4","title":"Time-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls...","description":"Time-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.","status":"published","published":"2026-09-15T18:32:26Z","modified":"2026-09-15T18:32:33Z","cvss":[{"version":"4.0","score":9,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"critical"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T15:11:54.134441Z"}],"nvd":[{"id":"CVE-2026-77972","description":"Time-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.","status":"published","published":"2026-09-15T16:17:24.29Z","modified":"2026-09-21T19:17:11.153Z","cvss":[{"version":"4.0","score":9,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"critical","assessor":"secondary"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T14:12:47.668237Z"}],"osv":[{"id":"CVE-2026-77972","title":"safeurl validated address is not bound to the request, allowing DNS rebinding","description":"Time-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.","status":"published","published":"2026-09-15T15:37:49.948Z","modified":"2026-10-28T02:31:02.631639543Z","cvss":[{"version":"4.0","score":9,"vector":"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","level":"critical"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T15:45:17.44708Z"},{"id":"EEF-CVE-2026-77972","title":"safeurl validated address is not bound to the request, allowing DNS rebinding","description":"## 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.","status":"published","published":"2026-09-15T15:37:49.948Z","modified":"2026-09-15T15:45:03.321931831Z","cvss":[{"version":"4.0","score":9,"vector":"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","level":"critical"}],"cwes":["CWE-367"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}