{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.1.0"
              },
              {
                "fixed": "0.6.1"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "ce7113a52efd04012c6f9e8d0b8267439f5fd6b8"
            },
            {
              "fixed": "36a82523e864739787340604f65ecce26699a0a9"
            },
            {
              "fixed": "84977e5b1a83f26e749d55ad06e3625464af4e8d"
            }
          ],
          "repo": "https://github.com/wojtekmach/req",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-655f-mp8p-96gv"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-409"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49755.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "e37753741cbdc725e6aba3d977b380163bfc0ecb"
          },
          {
            "fixed": "84977e5b1a83f26e749d55ad06e3625464af4e8d"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in wojtekmach Req allows attacker-controlled HTTP servers to exhaust memory in a Req client via decompression-bomb response bodies.\n\nReq's default response pipeline includes Req.Steps.decode_body/1 and Req.Steps.decompress_body/1 in lib/req/steps.ex. decode_body/1 dispatches on the server-supplied content-type (or URL extension) and calls :zip.extract(body, [:memory]) for application/zip, :erl_tar.extract({:binary, body}, [:memory]) for application/x-tar, and :erl_tar.extract({:binary, body}, [:memory, :compressed]) for application/gzip / .tgz. Each returns the full decompressed archive contents as a [{name, bytes}] list in memory, with no per-entry or total size cap. decompress_body/1 walks the content-encoding header and chains :zlib/:brotli/:ezstd decoders, so a response advertising content-encoding: gzip, gzip, gzip inflates through multiple layers without bound.\n\nBoth steps are enabled by default, no caller opt-in is required, and the attacker controls the content-type and content-encoding headers on their own server (or on any host reached via Req's automatic redirect following). A sub-megabyte response can expand to multiple gigabytes on the victim, crashing the BEAM process.\n\nThis issue affects req: from 0.1.0 before 0.6.1.",
  "id": "CVE-2026-49755",
  "modified": "2026-07-08T05:37:36.292569161Z",
  "published": "2026-06-08T15:20:57.415Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-49755.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-49755"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49755.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/wojtekmach/req/security/advisories/GHSA-655f-mp8p-96gv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49755"
    },
    {
      "type": "FIX",
      "url": "https://github.com/wojtekmach/req/commit/84977e5b1a83f26e749d55ad06e3625464af4e8d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/wojtekmach/req"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/wojtekmach/req.git"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Decompression bomb DoS in Req via auto-decoded archive and compressed response bodies"
}