FKIE_CVE-2026-27738

Vulnerability from fkie_nvd - Published: 2026-02-25 17:25 - Updated: 2026-04-15 00:35
Severity ?
6.9 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Summary
The Angular SSR is a server-rise rendering tool for Angular applications. An Open Redirect vulnerability exists in the internal URL processing logic in versions on the 19.x branch prior to 19.2.21, the 20.x branch prior to 20.3.17, and the 21.x branch prior to 21.1.5 and 21.2.0-rc.1. The logic normalizes URL segments by stripping leading slashes; however, it only removes a single leading slash. When an Angular SSR application is deployed behind a proxy that passes the `X-Forwarded-Prefix` header, an attacker can provide a value starting with three slashes. This vulnerability allows attackers to conduct large-scale phishing and SEO hijacking. In order to be vulnerable, the application must use Angular SSR, the application must have routes that perform internal redirects, the infrastructure (Reverse Proxy/CDN) must pass the `X-Forwarded-Prefix` header to the SSR process without sanitization, and the cache must not vary on the `X-Forwarded-Prefix` header. Versions 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21 contain a patch. Until the patch is applied, developers should sanitize the `X-Forwarded-Prefix` header in their`server.ts` before the Angular engine processes the request.
References
security-advisories@github.comhttps://github.com/angular/angular-cli/commit/877f017ace4b83277d773aa37f5813e5e9faec7e
security-advisories@github.comhttps://github.com/angular/angular-cli/issues/32501
security-advisories@github.comhttps://github.com/angular/angular-cli/pull/32521
security-advisories@github.comhttps://github.com/angular/angular-cli/security/advisories/GHSA-xh43-g2fq-wjrj
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/angular/angular-cli/issues/32501
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Angular SSR is a server-rise rendering tool for Angular applications. An Open Redirect vulnerability exists in the internal URL processing logic in versions on the 19.x branch prior to 19.2.21, the 20.x branch prior to 20.3.17, and the 21.x branch prior to 21.1.5 and 21.2.0-rc.1. The logic normalizes URL segments by stripping leading slashes; however, it only removes a single leading slash. When an Angular SSR application is deployed behind a proxy that passes the `X-Forwarded-Prefix` header, an attacker can provide a value starting with three slashes. This vulnerability allows attackers to conduct large-scale phishing and SEO hijacking. In order to be vulnerable, the application must use Angular SSR, the application must have routes that perform internal redirects, the infrastructure (Reverse Proxy/CDN) must pass the `X-Forwarded-Prefix` header to the SSR process without sanitization, and the cache must not vary on the `X-Forwarded-Prefix` header. Versions 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21 contain a patch. Until the patch is applied, developers should sanitize the `X-Forwarded-Prefix` header in their`server.ts` before the Angular engine processes the request."
    },
    {
      "lang": "es",
      "value": "El Angular SSR es una herramienta de renderizado del lado del servidor para aplicaciones Angular. Una vulnerabilidad de redirecci\u00f3n abierta existe en la l\u00f3gica interna de procesamiento de URL en versiones de la rama 19.x anteriores a la 19.2.21, la rama 20.x anteriores a la 20.3.17, y la rama 21.x anteriores a la 21.1.5 y 21.2.0-rc.1. La l\u00f3gica normaliza los segmentos de URL eliminando las barras iniciales; sin embargo, solo elimina una \u00fanica barra inicial. Cuando una aplicaci\u00f3n Angular SSR se despliega detr\u00e1s de un proxy que pasa el encabezado `X-Forwarded-Prefix`, un atacante puede proporcionar un valor que comienza con tres barras. Esta vulnerabilidad permite a los atacantes realizar phishing a gran escala y secuestro de SEO. Para ser vulnerable, la aplicaci\u00f3n debe usar Angular SSR, la aplicaci\u00f3n debe tener rutas que realicen redirecciones internas, la infraestructura (Proxy Inverso/CDN) debe pasar el encabezado `X-Forwarded-Prefix` al proceso SSR sin sanitizaci\u00f3n, y la cach\u00e9 no debe variar seg\u00fan el encabezado `X-Forwarded-Prefix`. Las versiones 21.2.0-rc.1, 21.1.5, 20.3.17 y 19.2.21 contienen un parche. Hasta que se aplique el parche, los desarrolladores deben sanear el encabezado `X-Forwarded-Prefix` en su \u0027server.ts\u0027 antes de que el motor de Angular procese la solicitud."
    }
  ],
  "id": "CVE-2026-27738",
  "lastModified": "2026-04-15T00:35:42.020",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.9,
          "baseSeverity": "MEDIUM",
          "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": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/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": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-02-25T17:25:40.463",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/angular/angular-cli/commit/877f017ace4b83277d773aa37f5813e5e9faec7e"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/angular/angular-cli/issues/32501"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/angular/angular-cli/pull/32521"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/angular/angular-cli/security/advisories/GHSA-xh43-g2fq-wjrj"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/angular/angular-cli/issues/32501"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-601"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}


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