FKIE_CVE-2026-118517

Vulnerability from fkie_nvd - Published: 2026-11-05 17:17 - Updated: 2026-11-06 21:40
Severity
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Summary
The Symfony HtmlSanitizer component UrlSanitizer parses URLs differently from browsers, allowing the allowLinkHosts() and allowMediaHosts() checks to be bypassed for URLs without a well-formed authority, resulting in untrusted hosts being referenced in sanitized output in Symfony versions 6.1.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. UrlSanitizer parses URLs with league/uri, which follows RFC 3986, while browsers follow the WHATWG URL standard. For URLs without a well-formed authority, such as http:evil.example, ///evil.example, or https://://evil.example/ the sanitizer finds no host, whereas browsers resolve them to evil.example. The guard added for CVE-2026-45066 missed the zero-slash form, and the host 0 was also skipped because PHP treats it as falsy. This is exploitable when a host allow-list is combined with allowRelativeLinks(true) or allowRelativeMedias(true). The default configuration is not affected.
References
596c5446-0ce5-4ba2-aa66-48b3b757a647https://github.com/symfony/symfony/commit/f2f47d2eef6c2552c6c5c24953caa94f7901cb43
596c5446-0ce5-4ba2-aa66-48b3b757a647https://github.com/symfony/symfony/security/advisories/GHSA-c76g-9c4c-gxrw
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://packagist.org/packages/symfony/http-client",
          "defaultStatus": "unaffected",
          "modules": [
            "Symfony\\Component\\HtmlSanitizer\\TextSanitizer\\UrlSanitizer"
          ],
          "packageName": "symfony/http-client",
          "product": "symfony",
          "repo": "https://github.com/symfony/http-client",
          "vendor": "sensiolabs",
          "versions": [
            {
              "lessThan": "6.4.50",
              "status": "affected",
              "version": "6.1.0",
              "versionType": "git"
            },
            {
              "lessThan": "7.4.23",
              "status": "affected",
              "version": "7.0.0",
              "versionType": "git"
            },
            {
              "lessThan": "8.1.11",
              "status": "affected",
              "version": "8.0.0",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "596c5446-0ce5-4ba2-aa66-48b3b757a647"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Symfony HtmlSanitizer component UrlSanitizer\u00a0parses URLs differently from browsers, allowing\u00a0the allowLinkHosts() and allowMediaHosts() checks to be bypassed for URLs without a well-formed authority,\u00a0resulting in untrusted hosts being referenced in sanitized output\u00a0in Symfony versions 6.1.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.\n\n\n\nUrlSanitizer parses URLs with league/uri, which follows RFC 3986, while browsers follow the WHATWG URL standard.\u00a0For URLs without a well-formed authority, such as http:evil.example, ///evil.example, or https://://evil.example/\u00a0the sanitizer finds no host, whereas browsers resolve them to evil.example. The guard added for CVE-2026-45066 missed the zero-slash form, and the host 0 was also skipped because PHP treats it as falsy.\n\n\n\nThis is exploitable when a host allow-list is combined with allowRelativeLinks(true) or allowRelativeMedias(true). The default configuration is not affected."
    }
  ],
  "id": "CVE-2026-118517",
  "lastModified": "2026-11-06T21:40:43.450",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 2.3,
          "baseSeverity": "LOW",
          "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": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/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": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "596c5446-0ce5-4ba2-aa66-48b3b757a647",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-118517",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-11-05T16:49:56.410466Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-11-05T17:17:53.147",
  "references": [
    {
      "source": "596c5446-0ce5-4ba2-aa66-48b3b757a647",
      "url": "https://github.com/symfony/symfony/commit/f2f47d2eef6c2552c6c5c24953caa94f7901cb43"
    },
    {
      "source": "596c5446-0ce5-4ba2-aa66-48b3b757a647",
      "url": "https://github.com/symfony/symfony/security/advisories/GHSA-c76g-9c4c-gxrw"
    }
  ],
  "sourceIdentifier": "596c5446-0ce5-4ba2-aa66-48b3b757a647",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-184"
        },
        {
          "lang": "en",
          "value": "CWE-436"
        }
      ],
      "source": "596c5446-0ce5-4ba2-aa66-48b3b757a647",
      "type": "Secondary"
    }
  ]
}



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