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github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files

Type: advisorySources: OSV

The `github.com/moby/sys/user` package provides Go utilities for parsing and looking up entries in Unix-style user and group database files. Versions before 0.4.1 do not sufficiently limit entries when parsing `/etc/passwd`- or `/etc/group`-style files, allowing an attacker who can supply a specially crafted file to cause excessive memory consumption and potentially terminate the affected process due to an out-of-memory condition. This issue is patched in version 0.4.1. As a workaround, avoid parsing attacker-controlled user or group database files, or validate and limit untrusted input before parsing it.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-61801
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 06:13 UTC · Revision 1

Source evidence

github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files

core-osv · Original source

Published 8 Oct 2026, 16:22 UTC

The `github.com/moby/sys/user` package provides Go utilities for parsing and looking up entries in Unix-style user and group database files. Versions before 0.4.1 do not sufficiently limit entries when parsing `/etc/passwd`- or `/etc/group`-style files, allowing an attacker who can supply a specially crafted file to cause excessive memory consumption and potentially terminate the affected process due to an out-of-memory condition. This issue is patched in version 0.4.1. As a workaround, avoid parsing attacker-controlled user or group database files, or validate and limit untrusted input before parsing it.

osv:CVE-2026-61801
Complete source record
{
  "id": "39ddd2c4cda8004376e7dde1762fe8c8bb7ffaa11aa3d052e5d5926e1aedd719",
  "url": "https://osv.dev/vulnerability/CVE-2026-61801",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files",
    "summary": "The `github.com/moby/sys/user` package provides Go utilities for parsing and looking up entries in Unix-style user and group database files. Versions before 0.4.1 do not sufficiently limit entries when parsing `/etc/passwd`- or `/etc/group`-style files, allowing an attacker who can supply a specially crafted file to cause excessive memory consumption and potentially terminate the affected process due to an out-of-memory condition. This issue is patched in version 0.4.1. As a workaround, avoid parsing attacker-controlled user or group database files, or validate and limit untrusted input before parsing it.",
    "evidence": "osv:CVE-2026-61801",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-61801",
      "aliases": [
        "CVE-2026-61801",
        "GHSA-mjcv-p78q-w5fw",
        "GO-2026-6686"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/moby/sys",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "85a71bbe1faa36c552a960e6a5f3d0cfb632fbbe"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.4.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "85a71bbe1faa36c552a960e6a5f3d0cfb632fbbe"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.4.1"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "sequential/v0.7.0",
            "mount/v0.3.5",
            "devices/v0.1.0",
            "atomicwriter/v0.1.0",
            "user/v0.4.0",
            "reexec/v0.1.0",
            "capability/v0.4.0",
            "capability/v0.3.0",
            "capability/v0.2.0",
            "userns/v0.1.0",
            "user/v0.3.0",
            "user/v0.2.0",
            "mount/v0.3.4",
            "symlink/v0.3.0",
            "signal/v0.7.1",
            "sequential/v0.6.0",
            "mountinfo/v0.7.2",
            "mountinfo/v0.7.1",
            "mountinfo/v0.7.0",
            "user/v0.1.0",
            "sequential/v0.5.0",
            "mount/v0.3.3",
            "mountinfo/v0.6.2",
            "mount/v0.3.2",
            "mountinfo/v0.6.1",
            "signal/v0.7.0",
            "mount/v0.3.1",
            "mountinfo/v0.6.0",
            "symlink/v0.2.0",
            "signal/v0.6.0",
            "mount/v0.3.0",
            "mountinfo/v0.5.0",
            "signal/v0.5.0",
            "mountinfo/v0.4.1",
            "mount/v0.2.0",
            "symlink/v0.1.0",
            "mountinfo/v0.4.0",
            "mountinfo/v0.3.1",
            "mountinfo/v0.3.0",
            "mountinfo/v0.2.0",
            "mount/v0.1.1",
            "mountinfo/v0.1.3",
            "mountinfo/v0.1.2",
            "mount/v0.1.0",
            "mountinfo/v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-61801.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.113622223Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61801.json",
        "https://github.com/moby/sys/security/advisories/GHSA-mjcv-p78q-w5fw",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-61801",
        "https://github.com/moby/sys/commit/85a71bbe1faa36c552a960e6a5f3d0cfb632fbbe",
        "https://github.com/moby/sys/pull/221"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-400"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61801.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-61801",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492973,
  "published_at": "2026-10-08T16:22:25.558+00:00"
}