BusyBox httpd Username Enumeration via System Password Auth
CVE-2026-88834 Published on October 13, 2026
Busybox: busybox: httpd user existence oracle in non-default shadow-disabled builds
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.
Vulnerability Analysis
CVE-2026-88834 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Timeline
Reported to Red Hat.
Made public. 34 days later.
Weakness Type
What is a Side Channel Attack Vulnerability?
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not. Discrepancies can take many forms, and variations may be detectable in timing, control flow, communications such as replies or requests, or general behavior. These discrepancies can reveal information about the product's operation or internal state to an unauthorized actor. In some cases, discrepancies can be used by attackers to form a side channel.
CVE-2026-88834 has been classified to as a Side Channel Attack vulnerability or weakness.
Products Associated with CVE-2026-88834
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