Zapros has an Unbounded Content-Encoding decompression chain that allows denial of service

{
  "id": "78ce99832fc0298cefee2ac7201d143052e859d77b9d37b59f9245bcb2289c07",
  "url": "https://osv.dev/vulnerability/CVE-2026-61541",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Zapros has an Unbounded Content-Encoding decompression chain that allows denial of service",
    "summary": "Zapros, a Python HTTP client, prior to version 0.14.0 is vulnerable to denial of service when an application requests content from an untrusted server, or follows a redirect to one, because a malicious response containing an excessive number of chained `Content-Encoding` values causes Zapros to construct a deeply nested decompression chain that consumes excessive resources. Version 0.14.0 patches the vulnerability by limiting responses to five content-encoding layers and raising `DecodingError` when that limit is exceeded. As a workaround, applications can add response middleware that inspects the `Content-Encoding` header and rejects responses containing more than a safe number of encoding layers.",
    "evidence": "osv:CVE-2026-61541",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-61541",
      "aliases": [
        "CVE-2026-61541",
        "GHSA-5vjj-2r48-q622",
        "PYSEC-2026-4181"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/kap-sh/zapros",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "ac1510f14665db5dcd806931f5511c8e5ac3ef63"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.14.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.14.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.13.0",
            "v0.12.0",
            "v0.11.1",
            "v0.11.0",
            "v0.10.0",
            "v0.9.0",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.1",
            "v0.5.0",
            "v0.4.0",
            "v0.3.0",
            "v0.2.3",
            "v0.2.2",
            "v0.2.1",
            "v0.2.0",
            "v0.1.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-61541.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.911074190Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61541.json",
        "https://github.com/kap-sh/zapros/security/advisories/GHSA-5vjj-2r48-q622",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-61541"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61541.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-61541",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 494336,
  "published_at": "2026-09-21T21:21:21.321+00:00"
}