# CVE-2026-63418: Monitoring Plugins check_icmp: -H argument count overflow leads in setuid-root binary

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

Monitoring Plugins is a suite of plugins for monitoring applications. From 3.0.0-rc1 until 3.0.1, check_icmp stores the number of hosts supplied through -H or --Host on the command line, or through --extra-opts files containing Host= entries, in an unsigned short. More than 65,535 hosts wrap the counter, causing process_arguments() to allocate an undersized hosts array and then write subsequent entries out of bounds before main() calls setuid(getuid()). On installations where check_icmp is setuid root, a local low-privileged attacker can corrupt heap memory while the process still has root privileges; reliable privilege escalation has not been demonstrated. Installations that use cap_net_raw file capabilities instead of setuid are not exposed to the privilege-escalation consequence. This issue is fixed in version 3.0.1.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- monitoring-plugins / monitoring-plugins: >= 3.0.0-rc1, < 3.0.1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 7 (high); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: GitHub_M

- CVSS 3.1: 7 (high); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-190, CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/monitoring-plugins/monitoring-plugins/security/advisories/GHSA-xvvw-4j77-rp7q (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/monitoring-plugins/monitoring-plugins/commit/c35c12e58d326ffbd6cfb3c9097653f9f3fb2f4a (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/monitoring-plugins/monitoring-plugins/releases/tag/v3.0.1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/monitoring-plugins/monitoring-plugins/commit/c35c12e58d326ffbd6cfb3c9097653f9f3fb2f4a (security-advisories@github.com)

- https://github.com/monitoring-plugins/monitoring-plugins/releases/tag/v3.0.1 (security-advisories@github.com)

- https://github.com/monitoring-plugins/monitoring-plugins/security/advisories/GHSA-xvvw-4j77-rp7q (security-advisories@github.com)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-63418; retrieved 2026-11-03; source updated 2026-11-03

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63418; retrieved 2026-11-04; source updated 2026-11-03

Revision: 4c7c3051912ce44ff7a8fcf5d84d41634c3f967300b57fba17c7ffaec3fdaff3

Canonical: https://y2.dev/cve/CVE-2026-63418

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