Brotli certificate decompression can allocate up to 1 GiB before authentication

{
  "id": "4d23fe28442870eb9a27d15acd658efba9f2ac2df7981418111e3322bb4fff71",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0348",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Brotli certificate decompression can allocate up to 1 GiB before authentication",
    "summary": "The built-in Brotli certificate decompressor (enabled by the non-default `brotli` crate feature) bounded the size of the decompressed output, but accepted a peer-selected history window. Brotli's large-window extension was enabled, so a five-byte header could cause an allocation of 1 GiB. A peer can abort a process whose allocator cannot satisfy that request. No trusted certificate is required by the attacker. Affected configurations are: - clients that enable the `brotli` feature and connect to a malicious server, and - servers that enable the `brotli` feature and request client certificates. Applications that do not enable the `brotli` feature are not affected.",
    "evidence": "osv:RUSTSEC-2026-0348",
    "products": [
      {
        "name": {
          "value": "rustls",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.23.46",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "RUSTSEC-2026-0348",
      "aliases": [
        "GHSA-h2v8-394m-p7vv",
        "RUSTSEC-2026-0348"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.23.9"
                },
                {
                  "fixed": "0.23.46"
                }
              ]
            }
          ],
          "package": {
            "name": "rustls",
            "purl": "pkg:cargo/rustls",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0348.json",
            "categories": [
              "denial-of-service"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-14T13:30:02.480925286Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/rustls",
        "https://rustsec.org/advisories/RUSTSEC-2026-0348.html",
        "https://github.com/rustls/rustls/pull/3297"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 316315,
  "published_at": "2026-10-14T12:00:00+00:00"
}