Apple iOS EUVD-2026-77954

Requires the attacker to get a sandboxed application installed and executed on the target Apple device (iOS/iPadOS 26.7-and-earlier / macOS Sequoia <15.8 / macOS 27-line pre-26.7 / visionOS <27) - i.e., local code already running inside the app sandbox (UI:R, user must launch the app). No network vector and no elevated privileges are needed (AV:L, PR:N), but exploitation is fundamentally gated on delivering and running malicious app code on-device; impact is confined to reading restricted files (confidentiality only), not modification or denial of service. This limits realistic risk to scenarios where a user is tricked into installing a rogue app or where the bug is chained after an initial foothold.

This is a moderate-severity local sandbox-escape/information-disclosure flaw, not an urgent priority. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N, base 5.5) confirms the attack is local-only and requires a malicious app to already be running on the device, with impact limited to confidentiality (C:H) - reading restricted files outside the sandbox - with no integrity or availability effect. EPSS is very low at 0.17% (6th percentile), the CVE is NOT on CISA KEV, and no public exploit code was identified, so all real-world-exploitation signals point to low likelihood of opportunistic mass exploitation. No SSVC decision data was provided in the input. Signals are internally consistent: a local, C-only bug requiring attacker-controlled code on-device with EPSS/KEV/POC all indicating no active exploitation. The residual risk is that this class of sandbox-escape bug is valuable in chained iOS/macOS exploit paths (e.g., paired with an initial code-execution or a jailbreak/spyware chain), so it warrants routine patching but not emergency response.

An attacker publishes or sideloads a sandboxed app (e.g., via the App Store, TestFlight, or enterprise/MDM distribution) that a user installs and launches. Once running, the app abuses insufficient path validation to traverse outside its sandbox container and read restricted files - such as other apps' data or protected system files - that its entitlements should forbid. No public exploit code has been identified at time of analysis, and exploitation requires the user to run the malicious app (UI:R).