CVE-2026-55078: Coder Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2mg2-p7r7-g27f",
  "modified" : "2026-07-06T21:06:45Z",
  "published" : "2026-07-06T21:06:45Z",
  "aliases" : [ "CVE-2026-55078" ],
  "summary" : "Coder: Zip upload decompression lacks aggregate size limit, enabling denial of service",
  "details" : "### Summary\n\n`POST /api/v2/files` converts zip uploads to tar in memory via `CreateTarFromZip`, which enforced a per-entry size limit but no aggregate limit on total decompressed output, writing to an unbounded in-memory buffer.\n\n> **Note:** Exploitation requires authenticated file-upload access and the impact is limited to availability (denial of service).\n\n### Impact\n\nAn authenticated user could upload a zip within the 100 MiB upload limit but containing many highly compressible entries whose decompressed size exhausted memory, crashing `coderd` before any RBAC check. Repeated requests could keep the service unavailable. This is a denial of service; it does not allow data disclosure or code execution.\n\n### Patches\n\nThe fix adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression.\n\nThe fix was backported to all supported release lines:\n\n| Release line | Patched version |\n|---|---|\n| 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) |\n| 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) |\n| 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) |\n| 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) |\n\n### Workarounds\n\nRestrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of `coderd`.\n\n### Resources\n\n- Fix: #25877\n\n### Credits\n\nCoder would like to thank Anthropic's Security Team (ANT-2026-22438) for independently disclosing this issue!",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.34.0"
      }, {
        "fixed" : "2.34.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.33.0"
      }, {
        "fixed" : "2.33.8"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.30.0"
      }, {
        "fixed" : "2.32.7"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.17.0"
      }, {
        "fixed" : "2.29.17"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/security/advisories/GHSA-2mg2-p7r7-g27f"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/pull/25877"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/coder/coder"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-409", "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-06T21:06:45Z",
    "nvd_published_at" : null
  }
}