CVE-2026-53414

Executive Summary

CVE-2026-53414 is an unpatched buffer over-read vulnerability in the annotator function of Zoom Clients. A malicious meeting participant can trigger this flaw via network access to cause a denial of service (DoS) on another participant, likely crashing the vulnerable Zoom client process. The vulnerability requires user interaction (the target must be in a meeting/annotation context) but no privileges, and carries a CVSS score of 6.5 with high availability impact. As of this writing, no patch, public exploit, or CISA KEV listing exists, leaving all Zoom Client deployments potentially exposed.

Technical Analysis

The NVD description identifies a missing bounds check in the annotator function of Zoom Clients, resulting in a buffer over-read condition. This is classified under CWE-126 (Buffer Over-read), which occurs when a program reads data beyond the intended buffer boundary.

Vulnerability Mechanism: Buffer over-read vulnerabilities in annotation functions typically arise when the application processes annotations (e.g., drawing strokes, text overlays, or shared whiteboard content) without validating that incoming data lengths match the allocated buffer size. An attacker-controlled annotation payload could cause the client to read beyond the boundary of an allocated memory region, leading to an application crash (denial of service) or, in more severe cases, memory disclosure — although the CVSS vector indicates only availability impact (C:N/I:N/A:H), suggesting the primary observed outcome is a crash rather than information leakage.

Attack Surface:

• Network-based (AV:N): The attack is delivered over the network through Zoom's meeting infrastructure.
• Low complexity (AC:L): No special conditions are required beyond standard meeting participation.
• No privileges required (PR:N): The attacker only needs to be a meeting participant, not an administrator or host.
• User interaction required (UI:R): The target must be actively engaged — likely receiving or participating in an annotation session, or having annotation/sharing features enabled.

Affected Component: Insufficient technical detail is available regarding the exact code path, function name, or input format that triggers the flaw. The NVD description mentions only "the annotator function of Zoom Clients" without a more precise identifier. Per our accuracy rules, we do not fabricate function names or code locations.

Notable Observations:

• The EPSS score of 0.00276 indicates a low current exploitation probability in the wild (19.8th percentile).
• CISA KEV does not list this CVE.
• No patch, vendor advisory, or workaround has been published at the time of this report.
• Affected version range is unknown — this is a material gap in the intelligence picture.

Exploitation Scenarios

No public PoC or exploit code has been identified. The attack chain below is inferred strictly from the vulnerability class (CWE-126 buffer over-read in an annotation component) and the CVSS vector.

Attack Chain:

Step 1 — Reconnaissance / Target Identification:

• The attacker must identify a target Zoom user who is in or likely to join a meeting where annotation features (whiteboard, screen annotation, or collaborative annotation) are enabled.
• The attacker would need to be invited to or aware of a meeting where the target participates, or the attacker could initiate a meeting and invite the target.

Step 2 — Triggering the Flaw (Vulnerability-Class Level):

• The attacker first establishes a meeting session with the target (attacker joins as a participant or host).
• The attacker then engages the annotation/sharing feature and crafts annotation data (e.g., a specially malformed annotation payload, an oversized drawing operation, or a corrupt annotation metadata block) designed to exceed the expected boundary during parsing.
• Because the annotator function lacks a bounds check, the target's Zoom client reads beyond the allocated buffer when processing this crafted annotation data.

Step 3 — Payload Execution Method:

• At the buffer over-read vulnerability class, the "payload" is the malformed annotation data itself — no executable code is deployed. The goal is to force an out-of-bounds read that causes the client to dereference an invalid memory address, hit an access violation, and terminate abruptly.

Step 4 — Post-Exploitation Impact:

• The target's Zoom client crashes, disconnecting them from the meeting and denying access to the meeting service.
• If the crash occurs repeatedly (attacker re-triggers the flaw after victim reconnects), this becomes a persistent denial-of-service condition against the individual participant.
• The availability impact is rated High (A:H) per the CVSS vector, consistent with a client crash.
• No confidentiality impact (C:N) and no integrity impact (I:N) are indicated — an over-read may expose memory contents, but the CVSS scoring suggests this has not been demonstrated or is not considered exploitable for information disclosure in practice.

Limitations: No public PoC is available; this attack chain is inferred from the vulnerability class and CVSS attributes. The inability to reproduce or confirm the precise trigger conditions limits confidence in the exact exploitation flow.

Impact Assessment

Business Impact:

• Disruption of collaboration: A successful exploit breaks an active meeting by crashing the target's Zoom client, directly disrupting business communication and collaboration workflows.
• Repeated attack potential: Since no patch exists, an attacker can repeatedly target the same or multiple participants, effectively disabling them from joining meetings entirely.
• Reputational damage: If exploited broadly, this could erode trust in Zoom as a reliable communication platform.

Blast Radius:

• Any Zoom Client deployment (desktop, mobile, or web-based meeting clients) that supports annotation features is potentially exposed.
• Since affected version details are undisclosed, all Zoom Client installations should be considered at risk until a vendor advisory clarifies scope.

EPSS Context:

• EPSS of 0.00276 (19.8th percentile) indicates a relatively low probability of active exploitation in the next 30 days. However, this metric reflects current weaponization status, not the severity of the flaw if exploited.

CISA KEV: Not listed — no known exploitation in the wild per CISA's tracking.

Detection Guidance

Detection of this vulnerability is challenging because:

1. The trigger is an in-application parsing flaw — no network signature is inherently unique.
2. The malformed annotation data is transmitted through Zoom's encrypted protocol.
3. No specific indicators of compromise (IOCs) exist.

The following detection rules focus on post-exploitation effects (client crashes) and, where possible, anomalous annotation data flow.

Sigma Rule

title: Zoom Client Repeated Crash After Annotation Session
id: 4f7a2c9e-1b3d-4f5a-8e2d-6a9c1f3b5d7e
status: experimental
description: Detects repeated Zoom client process crashes within a short window, which may indicate exploitation of CVE-2026-53414 buffer over-read in the annotator function.
author: Valtersit Threat Intelligence
date: 2026/02/01
tags:
    - attack.t1499
    - cve.2026-53414
    - cwe.126
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\Zoom.exe'
            - '\ZoomIt.exe'
            - '\zoom.us\Zoom.exe'
        Description|contains: 'Zoom'
    filter:
        EventID: 4688
    timeframe: 5m
    condition: selection | count() by Image > 3
level: high
falsepositives:
    - Legitimate Zoom client crashes due to unrelated bugs or system instability
    - Users repeatedly re-launching Zoom after manual external crashes

YARA Rule

rule Zoom_Annotator_Buffer_Overread_CVE_2026_53414
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects Zoom client memory dump artifacts potentially indicating buffer over-read in annotator function"
        date = "2026-02-01"
        cve = "CVE-2026-53414"
        cwe = "CWE-126"
        severity = "high"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-53414"
    strings:
        $s1 = "annotator" ascii wide nocase
        $s2 = "annotation" ascii wide nocase
        $s3 = "whiteboard" ascii wide nocase
        $s4 = "drawing" ascii wide nocase
        $s5 = "0x0000000000000000" ascii
    condition:
        uint16(0) == 0x5A4D and  // "MZ" DOS header (PE file/dump)
        filesize > 10MB and
        2 of ($s1, $s2, $s3, $s4) and
        #s5 >= 50
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"Zoom Annotation Data - Potential CVE-2026-53414 Buffer Overread Trigger";
    flow:established;
    content:"|01 00 00 00|"; depth:4;
    pcre:"/annotat|whiteboard|drawing/i";
    classtype:attempted-dos;
    sid:2026534141;
    rev:1;
    metadata:cve CVE-2026-53414, cwe CWE-126, attack_target Zoom_Client, deployment Perimeter, signature_severity Major, created_at 2026-02-01;)

Note: Zoom traffic is typically TLS-encrypted; this rule operates on decrypted traffic (e.g., via SSL inspection) or on the initial unencrypted handshake/control-plane traffic. Detection efficacy on raw network traffic is low.

Elastic Detection

// Detect repeated Zoom client process exits within a short window
// which may indicate DoS exploitation attempts

sequence by host.name with maxspan=10m
  [ process where event.type == "start" and 
    process.name.toLowerCase() in ("zoom.exe", "zoom") ]
  [ process where event.type == "end" and 
    process.name.toLowerCase() in ("zoom.exe", "zoom") and 
    process.exit_code != 0 ]
  [ process where event.type == "start" and 
    process.name.toLowerCase() in ("zoom.exe", "zoom") ]
  [ process where event.type == "end" and 
    process.name.toLowerCase() in ("zoom.exe", "zoom") and 
    process.exit_code != 0 ]
  [ process where event.type == "start" and 
    process.name.toLowerCase() in ("zoom.exe", "zoom") ]

Splunk SPL Query

index=windows EventCode=4688 OR EventCode=4689
| where match(Image, "(?i)zoom\.exe") OR match(New_Process_Name, "(?i)zoom\.exe")
| eval crash=if(EventCode=4689, 1, 0)
| stats count(eval(crash=1)) as crash_count, count(eval(crash=0)) as start_count, 
        values(Computer) as host, values(Image) as process
    by _time, user
| bin _time span=5m
| where crash_count > 3
| table _time, user, host, process, crash_count, start_count
| sort - _time
| rename _time as Time, user as User, host as Host, process as Process, 
         crash_count as "Zoom Crash Count (5m)", start_count as "Zoom Start Count (5m)"

Wazuh OSSEC Rule

<group name="zoom,">
  <rule id="100534" level="12">
    <if_sid>550</if_sid>
    <field name="win.eventdata.image" type="pcre2">(?i)zoom\.exe</field>
    <field name="win.system.eventID" type="pcre2">^4689$</field>
    <options>no_full_log</options>
    <description>Zoom client process terminated unexpectedly - potential CVE-2026-53414 buffer over-read DoS</description>
    <group>cve-2026-53414,cwe-126,dos,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Status

UNPATCHED — No patch evidence from any tracked source (patch confidence: 0/4). The vendor has not published a fix, advisory, or mitigation as of the date of this report. Affected version details are not available from any source.

1) Immediate Mitigations (Protective Controls)

• Disable annotation features in Zoom settings where they are not strictly required for business operations. In the Zoom admin portal, restrict annotation capabilities for external participants.
• Restrict external meeting participation: If meetings are internal-only, configure Zoom to require authentication for all participants, reducing exposure to unauthenticated attackers.
• Monitor Zoom client stability: Deploy endpoint monitoring to alert on repeated Zoom crashes (see the Sigma, Elastic, and Splunk rules above). Investigate any pattern of targeted crashes against specific users.
• Educate users: Advise meeting hosts to disable screen sharing/annotation for participants when those features are not essential, and to lock meetings once all expected participants have joined.

2) Patch / Upgrade Steps

• Track vendor advisories: Monitor Zoom's security bulletin page (https://zoom.us/trust/security/security-bulletin) for updates related to CVE-2026-53414.
• Apply the vendor patch as soon as it is released: Once Zoom publishes a patched client version, deploy it enterprise-wide through managed update channels (Zoom Admin Portal, MDM, or SCCM).
• Verify patched versions: After updating, confirm installed client versions match the vendor's patched release notes.

3) Long-Term Hardening

• Enable automatic updates: Configure Zoom clients to auto-update to minimize the window of exposure when a patch is published.
• Network segmentation: Consider restricting Zoom traffic to managed network segments where feasible (note: Zoom's multi-party architecture makes this complex).
• Endpoint protection: Deploy EDR solutions that can detect anomaly patterns associated with memory corruption in meeting applications.
• Vulnerability management process: Re-scan Zoom client deployments when the vendor releases the patch; track unpatched endpoints for compliance.
• Incident response readiness: Prepare a response plan for targeted DoS attacks, including procedures for isolating affected users, collecting crash dumps for forensics, and notifying appropriate security teams.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-53414
2. CWE-126 Buffer Over-read: https://cwe.mitre.org/data/definitions/126.html
3. Zoom Security Bulletin (monitor for patch): https://zoom.us/trust/security/security-bulletin
4. CISA Known Exploited Vulnerabilities Catalog (not listed): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
5. FIRST CVSS Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Threat Actor Activity: No known threat actor campaigns or exploit-in-the-wild evidence identified as of the writing of this report. CISA KEV does not include this CVE. The EPSS score (0.00276, 19.8th percentile) suggests low immediate exploitation likelihood; however, the unpatched status and network reachability warrant vigilant monitoring.