What’s Vulnerable › Vulnerabilities

CVE-2026-88831: Busybox: busybox: httpd silently fails open when ip deny rules contain invalid cidr prefix lengths

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-23 · updated 2026-09-25
• Weakness: CWE-636

Description

BusyBox httpd IP deny rules with invalid CIDR prefix lengths fail open, leaving a parsed IP with a zeroed mask so the rule matches no clients.

Affected products

• Red Hat Hardened Images: all versions — fixed in 1.37.0-9.1.hum1

How to fix

Upgrade to a fixed version: Red Hat Hardened Images 1.37.0-9.1.hum1. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2026:72111
• https://access.redhat.com/security/cve/CVE-2026-88831
• https://bugzilla.redhat.com/show_bug.cgi?id=2531346

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