Vulnerability from bitnami_vulndb
Published
2024-03-06 10:59
Modified
2026-09-08 08:34
Summary
Details

ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "nginx",
        "purl": "pkg:bitnami/nginx"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.21.0"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "type": "CVSS_V3"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-3618"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:f5:nginx:*:*:*:*:*:*:*:*"
    ],
    "severity": "High"
  },
  "details": "ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A MiTM attacker having access to victim\u0027s traffic at the TCP/IP layer can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.",
  "id": "BIT-nginx-2021-3618",
  "modified": "2026-09-08T08:34:36.952Z",
  "published": "2024-03-06T10:59:22.065Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://alpaca-attack.com/"
    },
    {
      "type": "ADVISORY",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1975623"
    },
    {
      "type": "ADVISORY",
      "url": "https://lists.debian.org/debian-lts-announce/2022/11/msg00031.html"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-3618"
    }
  ],
  "schema_version": "1.5.0"
}



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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

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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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