Zoom Clients CVE-2026-53413

The attacker must be an active participant in the same Zoom meeting as the victim - this co-participation requirement is the primary positional prerequisite, implied by the description's phrasing 'meeting participant to achieve remote code execution of another participant.' The annotation feature must be accessible and active within the meeting context; if annotation is disabled at the account or meeting level, the vulnerable code path is not reachable. CVSS UI:R confirms that some form of victim interaction is required, though the exact triggering action is not specified in available data - it may involve the victim viewing or interacting with annotated content. CVSS AC:H indicates that exploitation is not straightforward and requires the attacker to clear technical hurdles such as defeating memory protections or achieving precise memory layout conditions. What limits exploitation: attacker must share a meeting with the victim (not a generic internet-facing endpoint), exploitation complexity is high (AC:H), victim interaction is required (UI:R), and the annotation feature must be reachable - all of which constrain opportunistic or automated mass exploitation.

CVSS 8.3 (High) with vector AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H presents a nuanced risk picture. The high impact triad (C:H/I:H/A:H) and changed scope (S:C) reflect full-system RCE potential, which is severe. However, AC:H and UI:R are meaningful mitigators: exploitation is not trivial and requires the attacker to overcome technical precision challenges (typical for memory-corruption exploits) while also depending on some form of victim interaction with the annotation subsystem. PR:N confirms no Zoom-level authentication barriers for the attacker beyond meeting participation. No EPSS data is available to quantify exploitation probability. The vulnerability is absent from CISA KEV, meaning no confirmed active exploitation has been reported. No public proof-of-concept is known. Taken together, this is a genuine high-severity flaw with real RCE capability, but not currently exhibiting mass or opportunistic exploitation patterns - risk is highest for targeted attacks against high-value individuals in Zoom meetings. The implicit requirement to share a meeting with the victim substantially limits unauthenticated internet-scale exploitation.

An attacker joins a Zoom meeting - either by obtaining a meeting link or being invited - as a legitimate participant alongside the target victim. The attacker sends specially crafted annotation data designed to trigger the missing bounds check in the annotator function on the victim's Zoom client. If successful, the buffer over-write corrupts critical memory structures, redirecting execution flow to attacker-controlled code and achieving remote code execution on the victim's device at the privilege level of the Zoom process. No public proof-of-concept has been identified, and the AC:H rating suggests reliable exploitation requires non-trivial memory layout knowledge or timing precision.