How severe is CVE-2026-61801?

CVE-2026-61801 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-61801?

CVE-2026-61801 affects the following packages: github.com/moby/sys/user (Go). Ecosystems affected: Go.

How do I fix CVE-2026-61801?

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 CVE-2026-61801 is resolved across your whole dependency graph.

How do I detect CVE-2026-61801 in my Go dependencies?

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.

How do I mitigate CVE-2026-61801 if there is no patch (or I can't update yet)?

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.

Is CVE-2026-61801 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-61801 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-61801?

CVE-2026-61801 has an EPSS (Exploit Prediction Scoring System) score of 0.1%, placing it in the 1th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-61801?

CVE-2026-61801 is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-61801 published, and has it been updated?

CVE-2026-61801 was published on October 8, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2026-61801 — user

MEDIUMFix: moby/sys@85a71bb

CVE-2026-61801 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.

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

Also known asGHSA-mjcv-p78q-w5fwGO-2026-6686

Published

Oct 8, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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 CVE-2026-61801.

EPSS Exploitation Probability

via FIRST.org ↗

0.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs1th percentile — riskier than 1% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-61801 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

1 pkg affected

🐹github.com/moby/sys/user

Real-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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/moby/sys/user`	all versions	0.4.1`go get github.com/moby/sys/user@v0.4.1`

Detection & mitigation playbook

Open-source dependency

Detect
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 CVE-2026-61801 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.

Red HatModerate

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…

Workaround published by 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 CVE-2026-61801 (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

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](https://github.com/containerd/containerd/security/advisories/GHSA-jpcc-p29g-p8mq), which describes one practical exploitation path through processing untrusted contai