CVE-2026-77972 (GCVE-0-2026-77972)
Vulnerability from cvelistv5 – Published: 2026-09-15 15:37 – Updated: 2026-09-15 15:37
VLAI
EPSS
VEX
Title
safeurl validated address is not bound to the request, allowing DNS rebinding
Summary
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.
Validation 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.
This issue affects safeurl: from 0.1.0 onward.
Severity
CWE
- CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-77972.html | relatedthird-party-advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-77972 | related |
| https://github.com/slab/safeurl-elixir/commit/fea… | related |
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.SafeURL\u0027",
"\u0027Elixir.SafeURL.HTTPoison\u0027",
"\u0027Elixir.SafeURL.TeslaMiddleware\u0027"
],
"packageName": "safeurl",
"packageURL": "pkg:hex/safeurl",
"product": "safeurl",
"programFiles": [
"lib/safeurl/safeurl.ex",
"lib/safeurl/httpoison.ex",
"lib/safeurl/tesla_middleware.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.SafeURL\u0027:validate/2"
},
{
"name": "\u0027Elixir.SafeURL.HTTPoison\u0027:get/3"
},
{
"name": "\u0027Elixir.SafeURL.TeslaMiddleware\u0027:call/3"
}
],
"repo": "https://github.com/slab/safeurl-elixir",
"vendor": "Slab",
"versions": [
{
"lessThan": "*",
"status": "affected",
"version": "0.1.0",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.SafeURL\u0027",
"\u0027Elixir.SafeURL.HTTPoison\u0027",
"\u0027Elixir.SafeURL.TeslaMiddleware\u0027"
],
"packageName": "slab/safeurl-elixir",
"packageURL": "pkg:github/slab/safeurl-elixir",
"product": "safeurl",
"programFiles": [
"lib/safeurl/safeurl.ex",
"lib/safeurl/httpoison.ex",
"lib/safeurl/tesla_middleware.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.SafeURL\u0027:validate/2"
},
{
"name": "\u0027Elixir.SafeURL.HTTPoison\u0027:get/3"
},
{
"name": "\u0027Elixir.SafeURL.TeslaMiddleware\u0027:call/3"
}
],
"repo": "https://github.com/slab/safeurl-elixir",
"vendor": "Slab",
"versions": [
{
"lessThan": "*",
"status": "affected",
"version": "feabbd0a13f83028ab24b71710526e9da9841f70",
"versionType": "git"
}
]
}
],
"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 M\u00e4nnchen / EEF"
},
{
"lang": "en",
"type": "coordinator",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eTime-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname\u0027s DNS responses to reach internal network destinations that validation rejected.\u003c/p\u003e\n\u003cp\u003eValidation 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.\u003c/p\u003e\n\u003cp\u003eThis issue affects safeurl: from 0.1.0 onward.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "Time-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname\u0027s 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."
}
],
"value": "Time-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname\u0027s 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."
}
],
"impacts": [
{
"capecId": "CAPEC-664",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-664 Server Side Request Forgery"
}
]
}
],
"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": {
"dateUpdated": "2026-09-15T15:37:49.948Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"name": "EEF CNA record for CVE-2026-77972",
"tags": [
"related",
"third-party-advisory"
],
"url": "https://cna.erlef.org/cves/CVE-2026-77972.html"
},
{
"name": "OSV record EEF-CVE-2026-77972",
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-77972"
},
{
"name": "Introducing commit feabbd0 in slab/safeurl-elixir",
"tags": [
"related"
],
"url": "https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "safeurl validated address is not bound to the request, allowing DNS rebinding"
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-77972",
"datePublished": "2026-09-15T15:37:49.948Z",
"dateReserved": "2026-08-24T15:45:02.127Z",
"dateUpdated": "2026-09-15T15:37:49.948Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-77972",
"date": "2026-09-16",
"epss": "0.00317",
"percentile": "0.24629"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-77972\",\"sourceIdentifier\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"published\":\"2026-09-15T16:17:24.290\",\"lastModified\":\"2026-09-16T20:38:33.883\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Time-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname\u0027s 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\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"affectedData\":[{\"vendor\":\"Slab\",\"product\":\"safeurl\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://repo.hex.pm\",\"packageName\":\"safeurl\",\"cpes\":[\"cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*\"],\"modules\":[\"\u0027Elixir.SafeURL\u0027\",\"\u0027Elixir.SafeURL.HTTPoison\u0027\",\"\u0027Elixir.SafeURL.TeslaMiddleware\u0027\"],\"programFiles\":[\"lib/safeurl/safeurl.ex\",\"lib/safeurl/httpoison.ex\",\"lib/safeurl/tesla_middleware.ex\"],\"programRoutines\":[{\"name\":\"\u0027Elixir.SafeURL\u0027:validate/2\"},{\"name\":\"\u0027Elixir.SafeURL.HTTPoison\u0027:get/3\"},{\"name\":\"\u0027Elixir.SafeURL.TeslaMiddleware\u0027:call/3\"}],\"repo\":\"https://github.com/slab/safeurl-elixir\",\"packageURL\":\"pkg:hex/safeurl\",\"versions\":[{\"version\":\"0.1.0\",\"lessThan\":\"*\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Slab\",\"product\":\"safeurl\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://github.com\",\"packageName\":\"slab/safeurl-elixir\",\"cpes\":[\"cpe:2.3:a:slab:safeurl:*:*:*:*:*:*:*:*\"],\"modules\":[\"\u0027Elixir.SafeURL\u0027\",\"\u0027Elixir.SafeURL.HTTPoison\u0027\",\"\u0027Elixir.SafeURL.TeslaMiddleware\u0027\"],\"programFiles\":[\"lib/safeurl/safeurl.ex\",\"lib/safeurl/httpoison.ex\",\"lib/safeurl/tesla_middleware.ex\"],\"programRoutines\":[{\"name\":\"\u0027Elixir.SafeURL\u0027:validate/2\"},{\"name\":\"\u0027Elixir.SafeURL.HTTPoison\u0027:get/3\"},{\"name\":\"\u0027Elixir.SafeURL.TeslaMiddleware\u0027:call/3\"}],\"repo\":\"https://github.com/slab/safeurl-elixir\",\"packageURL\":\"pkg:github/slab/safeurl-elixir\",\"versions\":[{\"version\":\"feabbd0a13f83028ab24b71710526e9da9841f70\",\"lessThan\":\"*\",\"versionType\":\"git\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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/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\",\"baseScore\":9.0,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"LOW\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"HIGH\",\"subIntegrityImpact\":\"LOW\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-367\"}]}],\"references\":[{\"url\":\"https://cna.erlef.org/cves/CVE-2026-77972.html\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://osv.dev/vulnerability/EEF-CVE-2026-77972\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"}]}}"
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…