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PatchSiren cyber security CVE debrief

CVE-2026-88831 Red Hat CVE debrief

CVE-2026-88831 debrief based on the supplied source corpus. 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. This vulnerability affects defenders responsible for BusyBox httpd configurations, who should assess exposure and verify the effectiveness of current IP deny rules. The CVE record and NVD entry provide limited information about the vulnerability, and defenders need to verify exposure in BusyBox httpd configurations and assess the effectiveness of current IP deny rules.

Vendor
Red Hat
Product
Red Hat Hardened Images
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-23
Original CVE updated
2026-09-25
Advisory published
2026-09-23
Advisory updated
2026-09-25

Who should care

Defenders responsible for BusyBox httpd configurations should assess exposure and verify the effectiveness of current IP deny rules. They should prioritize verifying exposure in BusyBox httpd configurations and assessing the effectiveness of current IP deny rules. This vulnerability affects operators, platforms, vulnerability-management, and security teams that use BusyBox httpd.

Why it matters

CVE-2026-88831 is a vulnerability in BusyBox httpd where IP deny rules with invalid CIDR prefix lengths fail open. Defenders should prioritize verifying exposure in BusyBox httpd configurations and assessing the effectiveness of current IP deny rules.

  • Defenders need to verify exposure in BusyBox httpd configurations
  • Assess the effectiveness of current IP deny rules
  • Consider updating BusyBox httpd to a version that handles invalid CIDR prefix lengths correctly

Technical summary

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. This vulnerability affects BusyBox httpd configurations, and defenders should prioritize verifying exposure and assessing the effectiveness of current IP deny rules. The CVE record and NVD entry provide limited information about the vulnerability.

Defensive priority

Defenders should prioritize verifying exposure in BusyBox httpd configurations and assessing the effectiveness of current IP deny rules.

Recommended defensive actions

  • Verify BusyBox httpd configurations for IP deny rules with invalid CIDR prefix lengths
  • Assess the effectiveness of current IP deny rules
  • Consider updating BusyBox httpd to a version that handles invalid CIDR prefix lengths correctly

Evidence notes

The CVE record and NVD entry provide limited information about the vulnerability. 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.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-88831 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-88831

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-88831 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-88831

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.