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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.5 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-61801: 0.12% estimated exploitation activity in the next 30 days; percentile 1.65 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

8 Oct 2026, 16:08 UTC

Last modified by the source

19 Oct 2026, 21:31 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mjcv-p78q-w5fw

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6686

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mjcv-p78q-w5fw

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# Patch Next advisory brief: CVE-2026-61801

Advisory: github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database files
IDs: CVE-2026-61801, GHSA-mjcv-p78q-w5fw
Record: https://patchnext.com/advisories/cve-2026-61801 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/moby/sys/user 0.4.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/moby/sys/user: affected <= 0.4.0; fixed in 0.4.1

## Suggested inspection (read-only)
- Go github.com/moby/sys/user: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/moby/sys/user.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6686 (OSV record GO-2026-6686 lists affected ranges: Go github.com/moby/sys/user >=0 <0.4.1 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-mjcv-p78q-w5fw (OSV record GHSA-mjcv-p78q-w5fw lists affected ranges: Go github.com/moby/sys/user >=0 <0.4.1 (fixed))
- Verified: https://github.com/advisories/GHSA-mjcv-p78q-w5fw (GitHub-reviewed advisory GHSA-mjcv-p78q-w5fw lists affected ranges: Go github.com/moby/sys/user >=0 <=0.4.0)

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