Vulnerability · Published Sep 23, 2026 · Assigned by redhat
CVE-2026-88831Busybox: busybox: httpd silently fails open when ip deny rules contain invalid cidr prefix lengths
Medium 5.3
In plain English
A medium-severity security flaw in Red Hat Hardened Images from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.2%top 85.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | busybox | no fix listed | DEBIAN-CVE-2026-88831 |
| Debian:13 | busybox | no fix listed | DEBIAN-CVE-2026-88831 |
| Debian:14 | busybox | no fix listed | DEBIAN-CVE-2026-88831 |
| Ubuntu:22.04:LTS | busybox | no fix listed | UBUNTU-CVE-2026-88831 |
| Ubuntu:24.04:LTS | busybox | no fix listed | UBUNTU-CVE-2026-88831 |
| Ubuntu:26.04:LTS | busybox | no fix listed | UBUNTU-CVE-2026-88831 |
| Ubuntu:26.10 | busybox | no fix listed | UBUNTU-CVE-2026-88831 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Hardened Images | see references |
Weakness: CWE-636 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
References
- RHSA-2026:72111 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-88831 vdb-entry, x_refsource_REDHAT
- RHBZ#2531346 issue-tracking, x_refsource_REDHAT