GHSA-mjcv-p78q-w5fw github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files

• Go github.com/moby/sys/user: < 0.4.1 → fixed in 0.4.1

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. This issue is related to containerd [CVE-2026-47262] / 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. Impact `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. Applications 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. Patches This issue is fixed in `github.com/moby/sys/user` v0.4.1. Users should upgrade to v0.4.1 or later. Workarounds Avoid parsing attacker-controlled `/etc/passwd` or `/etc/group`-style files with affected versions of `github.com/moby/sys/user`. Applications 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. References • containerd CVE-2026-47262 / GHSA-jpcc-p29g-p8mq: https://github.com/containerd/containerd/security/advisories/GHSA-jpcc-p29g-p8mq • Fix in `github.com/moby/sys/user`: https://github.com/moby/sys/user/commit/210d32ba2bcb4544ee968c7f31249fe59796e60b