CVE-2026-88831CWE-636

CVE-2026-88831

Medium · published September 23, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
13.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00236 · 13.8th percentile
Weakness
CWE-636 · Not Failing Securely ('Failing Open')
Published
2026-09-23T22:17Z
References (3)
https://access.redhat.com/errata/RHSA-2026:72111 · [email protected]https://access.redhat.com/security/cve/CVE-2026-88831 · [email protected]https://bugzilla.redhat.com/show_bug.cgi?id=2531346 · [email protected]
EPSS history
Timeline
  • 25 SEP 03:28Z
    EPSS moved — → 0%
    epss
  • 23 SEP 17:45Z
    Busybox: busybox: httpd silently fails open when ip deny rules contain invalid cidr prefix lengths
    cvelistv5