Vulnerability-Lookup

CVE-2026-77972 (GCVE-0-2026-77972)

Vulnerability from cvelistv5 – Published: 2026-09-15 15:37 – Updated: 2026-09-21 18:44

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

9 (Critical)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-21 18:44 UTC

CWE

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

Assigner

EEF CNA under the mitre root

CNA scorecard A 97/100 over 345 records in the last 180 days details

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

2 products

Vendor	Product	Version	CPE status
Slab	safeurl	Affected: 0.1.0 , < * (semver) cpe:2.3:a:slab:safeurl::::::::
Slab	safeurl	Affected: feabbd0a13f83028ab24b71710526e9da9841f70 , < * (git) cpe:2.3:a:slab:safeurl::::::::

Credits

Jonatan Männchen / EEF Jonatan Männchen / EEF

Show details on NVD website

JSON

To clipboard

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                    }
                  ],
                  "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": "2026-09-21T18:44:16.787Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-77972

Vulnerability from fkie_nvd - Published: 2026-09-15 16:17 - Updated: 2026-09-21 19:17

Severity

9.0 (Critical) - 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

Summary

References

	URL	Tags
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://cna.erlef.org/cves/CVE-2026-77972.html
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://osv.dev/vulnerability/EEF-CVE-2026-77972

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "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"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "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."
    }
  ],
  "id": "CVE-2026-77972",
  "lastModified": "2026-09-21T19:17:11.153",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.0,
          "baseSeverity": "CRITICAL",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "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/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-77972",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-21T18:44:04.900610Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-15T16:17:24.290",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "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"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-367"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}

GHSA-PQWH-Q74P-W7H4

Vulnerability from github – Published: 2026-09-15 18:32 – Updated: 2026-09-15 18:32

Details

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

9.0 (Critical)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-77972"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-15T16:17:24Z",
    "severity": "CRITICAL"
  },
  "details": "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.",
  "id": "GHSA-pqwh-q74p-w7h4",
  "modified": "2026-09-15T18:32:26Z",
  "published": "2026-09-15T18:32:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77972"
    },
    {
      "type": "WEB",
      "url": "https://github.com/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-77972.html"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-77972"
    }
  ],
  "schema_version": "1.4.0",
  "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/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",
      "type": "CVSS_V4"
    }
  ]
}

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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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.

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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.

Action not permitted

CVE-2026-77972 (GCVE-0-2026-77972)

FKIE_CVE-2026-77972

GHSA-PQWH-Q74P-W7H4

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