CVE-2026-61801: Github.com/moby/sys/user Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mjcv-p78q-w5fw",
  "modified" : "2026-10-08T16:08:34Z",
  "published" : "2026-10-08T16:08:33Z",
  "aliases" : [ "CVE-2026-61801" ],
  "summary" : "github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files",
  "details" : "A denial-of-service (DoS) vulnerability exists in `github.com/moby/sys/user` before v0.4.1 when parsing specially crafted user or group database files. An attacker able to supply a malicious `/etc/passwd` or `/etc/group`-style file may cause excessive memory consumption, potentially resulting in process termination due to Out Of Memory (OOM) conditions.\n\nThis issue is related to containerd [CVE-2026-47262] / [GHSA-jpcc-p29g-p8mq](https://github.com/containerd/containerd/security/advisories/GHSA-jpcc-p29g-p8mq), which describes one practical exploitation path through processing untrusted container image content. Applications using `github.com/moby/sys/user` to parse untrusted user or group database files may be similarly affected.\n\n### Impact\n\n`github.com/moby/sys/user` versions before v0.4.1 do not place sufficient limits on entries while parsing user and group database files. A specially crafted file may cause excessive memory consumption, potentially leading to process termination due to Out Of Memory (OOM) conditions.\n\nApplications that use `github.com/moby/sys/user` to parse user-supplied or otherwise untrusted `/etc/passwd` or `/etc/group` files may be affected. The severity depends on whether an attacker can influence the contents of files being parsed.\n\n### Patches\n\nThis issue is fixed in `github.com/moby/sys/user` v0.4.1. Users should upgrade to v0.4.1 or later.\n\n### Workarounds\n\nAvoid parsing attacker-controlled `/etc/passwd` or `/etc/group`-style files with affected versions of `github.com/moby/sys/user`.\n\nApplications that must process untrusted user or group database files should validate and limit accepted input before parsing. Upgrading to v0.4.1 or later is the recommended remediation.\n\n### References\n\n* containerd CVE-2026-47262 / GHSA-jpcc-p29g-p8mq: https://github.com/containerd/containerd/security/advisories/GHSA-jpcc-p29g-p8mq\n* Fix in `github.com/moby/sys/user`: https://github.com/moby/sys/user/commit/210d32ba2bcb4544ee968c7f31249fe59796e60b",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/moby/sys/user"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.4.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.4.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/moby/sys/security/advisories/GHSA-mjcv-p78q-w5fw"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/moby/sys/pull/221"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/moby/sys/commit/85a71bbe1faa36c552a960e6a5f3d0cfb632fbbe"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/moby/sys"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-08T16:08:33Z",
    "nvd_published_at" : null
  }
}