Zoom has patched three memory corruption flaws in its annotation feature that allowed any meeting participant to execute code on another attendee's device with no interaction. The fixes shipped in June and July 2026, roughly two months before the research was made public.

The vulnerabilities affected the annotation tools used during screen sharing. An attacker on a call, whether an invited guest or the host, could send a specially crafted message that ran on other machines without a click, a prompt, or any visible sign. The discovery was made by a security firm that focuses on offensive research, and the findings were later coordinated with Zoom before disclosure.

Root cause: trusting annotation counts

The bugs are memory safety failures, not complicated logic errors. When a user shares their screen and uses annotation features, the underlying protocol sends a series of counts followed by data. The receiving client trusted those counts without adequate validation. In one case, a single value was able to overrun a 128-byte buffer and corrupt a return address. In a compiled application, corrupting a return address gives an attacker a direct path to change program flow and execute arbitrary code on the victim's machine.

A second flaw made the first one easier to exploit. The annotation dispatcher accepted messages without checking which participant had sent them. That meant a malicious participant did not need to spoof an identity or bypass a host permission check; the protocol simply did not enforce sender validation correctly. With these two issues combined, a participant could deliver the payload to other meeting attendees and have their machines execute it with no user interaction.

The third issue is also a memory corruption flaw in the same annotation subsystem. The security firm grouped all three together because they are triggered by the same protocol and have the same impact: remote code execution within the context of the Zoom client. Depending on the privileges of the user running Zoom, the attacker could gain a foothold into the underlying operating system and then move laterally inside a corporate network.

Affected versions and severity

Zoom has issued fixed builds for every main distribution channel. The patched versions are Zoom Workplace 7.1.5 and 7.0.6, Rooms and the Meeting SDK at 7.1.5, and the Windows VDI client at 7.0.11 and 6.6.16. Anything older at the time of disclosure remained exposed. Organizations running on-premises Zoom environments or custom Meeting SDK integrations need to verify that they have moved to one of these supported versions.

There is a gap between how the researchers and the vendor scored the vulnerabilities. The security firm that found the bugs rated all three as 9.0 out of 10 on the CVSS scale. Zoom, however, assigned CVE-2026-53413 and CVE-2026-53415 a score of 8.3 and CVE-2026-53414 a score of 6.5. The difference is not unusual; vendors and researchers often disagree about the practical exploitability, attack complexity, and potential impact of a bug. Zoom's lower score for one of the flaws may reflect the fact that it requires the attacker to be in a meeting and cannot be triggered without an active screen share.

The severity should not be understated. A 6.5 score is still a serious vulnerability, and an 8.3 is critical in most threat models. The important point is that the fixes were shipped before public disclosure, so users who updated in late summer were already protected when the details emerged.

Potential impact of exploitation

Remote code execution on a participant's machine can lead to a long list of secondary attacks. An attacker who successfully exploited one of these flaws could steal files, turn on the camera and microphone, harvest credentials and browser wallet data, install second-stage payloads, or use the infected machine as a pivot point into other systems. Because the flaw required no action from the target, it is particularly dangerous in large meetings where hundreds of attendees might be connected from personal laptops or corporate devices.

In a worst-case scenario, an attacker could join as a guest using a renamed account, wait for someone to start an annotation session, and then deploy an exploit silently. The victim would see nothing unusual on their screen. The annotation tool would continue to behave normally, which is why this class of vulnerability is often used in targeted attacks rather than mass exploitation.

Zoom has had a complicated security history. In the early days of the pandemic, the platform faced criticism for end-to-end encryption claims, Mac webcam vulnerabilities, and a range of privacy issues. Since then, the company has overhauled its security team, implemented a formal bug bounty program, and shipped numerous hardening updates for its video conferencing stack. The June and July fixes are part of that broader effort, but they also show that even mature collaboration tools carry memory safety issues in less obvious features.

The AI factor in finding and exploiting the bugs

What makes this case notable is the claim that AI did much of the exploitation work. The security firm said it went from the initial clues to a working exploit in under a day, using fewer than 20 prompts on publicly available AI models. That level of speed, the researchers said, was until recently the preserve of nation-state security agencies. OpenAI has also shipped a cyber-focused model trained to refuse less, signaling that AI-assisted vulnerability research is becoming a normal part of the security landscape.

However, the firm's own technical writeup complicates the narrative. An automated ranking pass across 3,762 functions missed the vulnerable library entirely. The code was placed at 45th on the list, so the initial AI-driven scan did not surface it. The bug only came to light when a researcher traced a live call by hand and followed the annotation data path. AI weaponized the vulnerability quickly, but a human found it. This is a useful reminder that AI is now a force multiplier for skilled researchers, not a replacement for them.

The broader trend is still real. Anthropic's Mythos, an AI system designed for security research, has reportedly found 10,000 critical vulnerabilities in a month. That volume is far larger than the industry can patch in the same period. Even when vendors move quickly, many enterprise environments run thousands of applications, and the gap between discovery, patch development, and deployment remains one of the biggest unsolved problems in cybersecurity.

What administrators and users should do now

For individual users, the safest move is to keep Zoom updated. The desktop client can be configured to check for updates automatically, but administrators should verify that version numbers match the fixed builds. On mobile devices, the issue is less severe because the annotation feature is primarily available in the desktop and VDI clients, but mobile users should still update regularly.

Enterprises should also consider restricting which participants can use annotation tools during large meetings. Zoom offers settings that allow hosts to limit annotations to specific users or disable them entirely. Since the vulnerability is in the annotation feature, reducing the attack surface can lower the risk in the period before a patch is deployed to every machine.

Security teams can also review their Zoom integration logs and meeting recordings for unusual annotation activity. While the attack leaves no on-screen trace, network forensics and endpoint detection tools may catch the execution of an unexpected process triggered by the Zoom client. Organizations that have already updated to 7.1.5 or 7.0.6, or the matching Rooms, SDK, and VDI releases, can consider themselves covered against the three publicized CVEs.

The timing of this disclosure is a case study in coordinated vulnerability research. The researchers gave Zoom enough time to patch the flaws, the fixes were widely distributed, and the public writeup came only after users had a reasonable chance to update. The result is that this is no longer an emergency for most organizations. The real lesson is that collaboration features remain a rich attack surface, and the combination of human intuition and AI assistance is driving both vulnerability discovery and exploitation at a speed that will continue to challenge security teams.

Source: TNW | Apps News