CVE-2026-88834: Busybox: busybox: httpd user existence oracle in non-default shadow-disabled builds

Severity: low (CVSS 3.7 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: 2026-10-13 · updated 2026-10-15
Weakness: CWE-203

Description

A flaw was found in BusyBox's httpd web server. When configured with system password authentication, a user existence oracle may exist in certain build configurations. An attacker could distinguish existing from non-existing usernames by observing authentication failure behavior. Impact is limited to username enumeration and requires non-default compile options or uncommon password file states; default BusyBox builds with shadow password support are not affected.

Affected products

Red Hat Hardened Images: all versions

References

https://access.redhat.com/security/cve/CVE-2026-88834
https://bugzilla.redhat.com/show_bug.cgi?id=2531348

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