github.com/moby/sys/user has a possible DoS via unbounded parsing of user and group database filesGHSA-mjcv-p78q-w5fw
MEDIUMFix: moby/sys#221GHSA-mjcv-p78q-w5fw is a medium-severity (CVSS 5.5) Uncontrolled Resource Consumption vulnerability in github.com/moby/sys/user. A fix is available for github.com/moby/sys/user — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-mjcv-p78q-w5fw.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-mjcv-p78q-w5fw by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
github.com/moby/sys/userReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/moby/sys/user | all versions | 0.4.1go get github.com/moby/sys/user@v0.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/moby/sys/user, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/moby/sys/user to 0.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mjcv-p78q-w5fw is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated as Moderate impact because exploitation requires supplying a malicious user or group database file to an affected tool, and the resulting impact is limited to an out-of-memory denial of service without compromising confidentiality, integrity, or elevating privileges. Across Red Hat…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for GHSA-mjcv-p78q-w5fw (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Hardened Images | grafana13-2-main-13.2.3-0.1.hum1 | RHSA-2026:76430 |
| Red Hat Hardened Images | grafana13-1-main-13.1.7-0.1.hum1 | RHSA-2026:76448 |
| Red Hat Hardened Images | grafana12-4-main-12.4.12-0.4.hum1 | RHSA-2026:76677 |
Frequently Asked Questions
Is GHSA-mjcv-p78q-w5fw in your dependencies?
Find it across Go, including transitive dependencies.