Skip to content
Fencer Vulns
medium 5.3

CVE-2026-88831 json

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

published 2026-09-23 46 d ago modified 2026-09-25 44 d ago also EUVD-2026-85509

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

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.

Patch / fix

  • Red Hat Red Hat Hardened Images 1.37.0-9.1.hum1
  • busybox hummingbird 1 1.37.0-9.1.hum1
  • busybox-shared hummingbird 1 1.37.0-9.1.hum1
  • busybox-petitboot hummingbird 1 1.37.0-9.1.hum1

red hat advisories RHSA-2026:72111

  • busybox SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 1.35.0-150400.3.23.1
  • busybox SLE Module for Basesystem 15 SP7 1.37.0-150700.18.24.1
  • busybox Linux Micro 6.0 1.36.1-159998.1.1
  • busybox SLES for SAP applications 16.0, SLES 16.0 1.37.0-160000.8.1
  • busybox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 1.35.0-10.12.1

suse advisories SUSE-SU-2026:4798-1SUSE-SU-2026:4773-1SUSE-SU-2026:4760-1SUSE-SU-2026:24137-1SUSE-SU-2026:24215-1

  • busybox openSUSE Leap 16.0 1.37.0-160000.8.1
  • busybox openSUSE Tumbleweed 1.38.0-3.1

opensuse advisories openSUSE-SU-2026:22067-1openSUSE-SU-2026:11954-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-88831 updated cvss 5.3

busybox: busybox: httpd silently fails open when IP deny rules contain invalid CIDR prefix lengths

  • Red Hat Hardened Images busybox 1.37.0-9.1.hum1, busybox-shared 1.37.0-9.1.hum1, busybox-petitboot 1.37.0-9.1.hum1
    fixed: vendor fix RHSA-2026:72111

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
46 d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected products

  • Red Hat Red Hat Hardened Images

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.