{"id":"CVE-2026-77972","state":"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.","publishedAt":"2026-09-15T15:37:49.948Z","updatedAt":"2026-09-21T18:44:16.787Z","severity":{"score":9,"label":"Critical","version":"4.0","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","source":"EEF"},"assigner":"EEF","products":["Slab safeurl"],"affected":[{"vendor":"Slab","product":"safeurl","packageName":"safeurl","packageURL":"pkg:hex/safeurl","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"*","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"],"modules":["'Elixir.SafeURL'","'Elixir.SafeURL.HTTPoison'","'Elixir.SafeURL.TeslaMiddleware'"],"programFiles":["lib/safeurl/safeurl.ex","lib/safeurl/httpoison.ex","lib/safeurl/tesla_middleware.ex"],"programRoutines":[{"name":"'Elixir.SafeURL':validate/2"},{"name":"'Elixir.SafeURL.HTTPoison':get/3"},{"name":"'Elixir.SafeURL.TeslaMiddleware':call/3"}],"repo":"https://github.com/slab/safeurl-elixir"},{"vendor":"Slab","product":"safeurl","packageName":"slab/safeurl-elixir","packageURL":"pkg:github/slab/safeurl-elixir","defaultStatus":"unaffected","versions":[{"version":"feabbd0a13f83028ab24b71710526e9da9841f70","status":"affected","lessThan":"*","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"],"modules":["'Elixir.SafeURL'","'Elixir.SafeURL.HTTPoison'","'Elixir.SafeURL.TeslaMiddleware'"],"programFiles":["lib/safeurl/safeurl.ex","lib/safeurl/httpoison.ex","lib/safeurl/tesla_middleware.ex"],"programRoutines":[{"name":"'Elixir.SafeURL':validate/2"},{"name":"'Elixir.SafeURL.HTTPoison':get/3"},{"name":"'Elixir.SafeURL.TeslaMiddleware':call/3"}],"repo":"https://github.com/slab/safeurl-elixir"}],"references":["https://cna.erlef.org/cves/CVE-2026-77972.html","https://osv.dev/vulnerability/EEF-CVE-2026-77972","https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70"],"weaknesses":["CWE-367"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77972.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77972","state":"PUBLISHED","datePublished":"2026-09-15T15:37:49.948Z","dateUpdated":"2026-09-21T18:44:16.787Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-08-24T15:45:02.127Z"},"containers":{"cna":{"title":"safeurl validated address is not bound to the request, allowing DNS rebinding","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Slab","product":"safeurl","packageName":"safeurl","packageURL":"pkg:hex/safeurl","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"*","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"],"modules":["'Elixir.SafeURL'","'Elixir.SafeURL.HTTPoison'","'Elixir.SafeURL.TeslaMiddleware'"],"programFiles":["lib/safeurl/safeurl.ex","lib/safeurl/httpoison.ex","lib/safeurl/tesla_middleware.ex"],"programRoutines":[{"name":"'Elixir.SafeURL':validate/2"},{"name":"'Elixir.SafeURL.HTTPoison':get/3"},{"name":"'Elixir.SafeURL.TeslaMiddleware':call/3"}],"repo":"https://github.com/slab/safeurl-elixir"},{"vendor":"Slab","product":"safeurl","packageName":"slab/safeurl-elixir","packageURL":"pkg:github/slab/safeurl-elixir","defaultStatus":"unaffected","versions":[{"version":"feabbd0a13f83028ab24b71710526e9da9841f70","status":"affected","lessThan":"*","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"],"modules":["'Elixir.SafeURL'","'Elixir.SafeURL.HTTPoison'","'Elixir.SafeURL.TeslaMiddleware'"],"programFiles":["lib/safeurl/safeurl.ex","lib/safeurl/httpoison.ex","lib/safeurl/tesla_middleware.ex"],"programRoutines":[{"name":"'Elixir.SafeURL':validate/2"},{"name":"'Elixir.SafeURL.HTTPoison':get/3"},{"name":"'Elixir.SafeURL.TeslaMiddleware':call/3"}],"repo":"https://github.com/slab/safeurl-elixir"}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-77972.html","name":"EEF CNA record for CVE-2026-77972","tags":["related","third-party-advisory"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-77972","name":"OSV record EEF-CVE-2026-77972","tags":["related"]},{"url":"https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70","name":"Introducing commit feabbd0 in slab/safeurl-elixir","tags":["related"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"HIGH","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":9,"baseSeverity":"CRITICAL","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"LOW","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-367","description":"CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-09-15T15:37:49.948Z"},"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*","versionStartIncluding":"0.1.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"reporter","value":"Jonatan Männchen / EEF"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-664","descriptions":[{"lang":"en","value":"CAPEC-664 Server Side Request Forgery"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-21T18:44:04.900610Z","id":"CVE-2026-77972","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-21T18:44:16.787Z"}}]}}}