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CVE-2026-53413, dubbed Zoomsday, is a zero-click remote code execution vulnerability in Zoom Clients’ annotation feature affecting clients on all supported platforms. The flaw is a memory corruption issue caused by a missing bounds check in the annotator logic, specifically described as a remotely triggerable stack buffer overflow in CAnnoFormatBlock::Deserialize. The vulnerable routine rebuilds annotation formatting objects from attacker-controlled network data and trusts a wire-controlled character count when copying into fixed-size 128-byte buffers. A malicious meeting participant can send a specially crafted annotation message that overflows the buffer, corrupts adjacent memory, and can hijack control flow. The issue is reachable through Zoom’s normal encrypted meeting transport and does not require victim interaction.
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No public exploit code observed for this vulnerability.
8 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A critical zero-click remote code execution vulnerability in Zoom's annotation feature caused by memory corruption / stack buffer overflow in CAnnoFormatBlock::Deserialize, allowing a meeting participant to execute code on another participant’s device without user interaction.
A high-severity remote code execution vulnerability in Zoom’s annotation feature caused by unsafe deserialization of formatting data into fixed-size buffers, enabling a malicious meeting participant to achieve zero-click code execution on another attendee’s machine.
A zero-click remote code execution vulnerability in Zoom’s annotator function caused by a missing bounds check leading to memory corruption.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.