Axis OS EUVD-2026-55964

Two explicit prerequisites must both be met for exploitation: (1) the Axis device must have the 'allow installation of unsigned ACAP applications' option enabled - this is a non-default configuration that must be deliberately activated by an administrator and represents a deliberate relaxation of the device's application trust policy; and (2) an attacker must successfully social-engineer a victim with application installation privileges (consistent with PR:H in the CVSS vector) into installing a malicious ACAP package. Beyond these gates, the race condition itself (AC:H) requires precise timing to win the TOCTOU window, adding further complexity. Exploitation is limited by: the non-default unsigned-app-installation setting (the primary gate), the requirement for administrative victim interaction, high attack complexity due to race condition timing constraints, no scope change (S:U - lateral movement to adjacent systems is not inherent to this vulnerability), and no availability impact. Organizations enforcing signed-only ACAP installation are not exposed.

The CVSS 3.1 score of 5.7 Medium is appropriately calibrated given the attack prerequisites. The network attack vector (AV:N) reflects that application installation may be initiated remotely via a web management interface, but this is heavily offset by high attack complexity (AC:H, race condition timing), high privilege requirements (PR:H, administrative-level victim), and mandatory user interaction (UI:R, the victim must actively install the malicious package). No EPSS data was provided, preventing probabilistic exploitation assessment; however, the absence of a KEV listing and the lack of any identified public proof-of-concept code both support low near-term exploitation likelihood. The most decisive risk limiter is the non-default configuration gate: devices that enforce signed-only ACAP installation are not exposed, and this is expected to be the majority of production deployments. Defenders should treat this as a medium-priority hardening action rather than an emergency patch, unless their environment has explicitly relaxed the signed-app policy.

An attacker targeting a surveillance network identifies an Axis device whose administrator has enabled unsigned ACAP application installation, then crafts a malicious ACAP package designed to exploit the TOCTOU window. The attacker socially engineers the device administrator - for example, by posing as a vendor providing a firmware utility or diagnostic tool - into initiating installation; during the brief interval between the framework's integrity check and application execution, the attacker replaces the checked package with the malicious payload, causing the device to execute attacker-controlled code with elevated privileges.