CVE-2026-108185

Executive Summary

CVE-2026-108185 is an improper certificate validation flaw (CWE-295) in the "My Notes" feature of certain Zoom Clients. An unauthenticated attacker with network access can exploit the missing/inadequate certificate check to conduct an information disclosure. The vulnerability is assigned a CVSS 3.1 base score of 7.4 (High), reflecting high confidentiality and integrity impact delivered over a network attack path with high attack complexity and no required privileges or user interaction. No public proof-of-concept, exploit code, Nuclei template, or CISA KEV entry exists as of this report, and no patch or affected-version data has been published by any tracked source.

Technical Analysis

The root cause is classified under CWE-295, "Improper Certificate Validation." In practice, this class of defect occurs when a client application establishes a TLS/SSL connection but fails to correctly perform one or more of the required validation steps: verifying the certificate chain up to a trusted root, validating the certificate's hostname/subject against the endpoint it intended to reach, checking the validity/expiration window, or validating certificate revocation status. When any of these checks is skipped or done incorrectly, the client will accept a certificate presented by an attacker-controlled or impersonated endpoint.

The affected component is the "My Notes" feature within "certain Zoom Clients." The NVD description explicitly states the impact is information disclosure and that exploitation requires "network access" and no authentication. This pattern is consistent with a client-side trust failure in which data associated with the My Notes feature — content synchronized to, retrieved from, or transmitted to a remote service — is exchanged with a server whose identity is not cryptographically verified. Because certificate validation is broken, an adversary positioned on the network path can interpose a server presenting an arbitrary certificate, and the vulnerable client will proceed with the connection rather than aborting.

The CVSS vector (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N) is materially informative and constrains how this must be interpreted:

• AV:N — the attack is mounted over a network, not via local access. The attacker needs network reachability to a path the client traverses.
• AC:H — the attacker must meet conditions beyond their direct control (for example, positioning on the network path, DNS/name resolution manipulation, or forcing the client to reach an attacker-influenced endpoint). This is why complexity is High despite no privileges or user interaction being required.
• PR:N / UI:N — no account on the target and no victim interaction are needed, which raises the silent-exploitation risk once the network precondition is met.
• C:H / I:H — high confidentiality and high integrity impact. Confidentiality loss aligns directly with the stated information disclosure. A high integrity rating is consistent with the attacker being able to substitute or feed attacker-chosen content/data into the trusting client as part of the broken-trust exchange.
• S:U — the impact is scoped to the vulnerable client component rather than a distinct security authority.

The exact TLS library, the specific certificate-check function, the underlying network endpoints, and the precise data field disclosed in "My Notes" are not disclosed in the NVD description or CNA title. Those implementation specifics should not be assumed and are noted here as insufficient technical detail available. What can be stated with confidence is the vulnerability class and mechanism: an unauthenticated, network-adjacent trust failure in a Zoom client component that leads to information disclosure.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class and the NVD description only. No function names, endpoints, or parameters are invented.

1. Reconnaissance / target identification. The attacker determines whether a target user or host runs an affected Zoom Client that exposes the vulnerable "My Notes" functionality, and identifies the network path along which that client communicates with its associated remote service. Because the CVE lacks an affected-version range, the attacker (and defenders) cannot rely on version fingerprinting alone; the attacker instead focuses on the network position and the service the My Notes client component contacts.

2. Triggering the specific flaw class. The attacker obtains a position on the network path between the vulnerable client and the remote endpoint it contacts for My Notes (for example, via a man-in-the-middle/AiTM position, DNS or name-resolution manipulation, or routing control). At the point of connection, the attacker presents a certificate that a correctly implemented client would reject — for example, one that is self-signed, issued for the wrong hostname, untrusted by the client's trust store, or otherwise invalid. Because the client performs improper certificate validation, it does not abort the connection and instead proceeds as if the endpoint were authentic. This is the CRITICAL step; it is gated by the AC:H precondition — the attacker must first achieve the network position and redirect/resolve the client to the attacker-controlled endpoint.

3. Payload/execution at the vulnerability-class level. Exploitation does not require a crafted memory-corruption payload; it is an abuse of the established trusted channel. The attacker's interposed endpoint simply responds to the client's requests for the My Notes functionality. Because the client believes it is talking to the legitimate service, it accepts and processes the attacker's responses, discloses information to the attacker, or ingests attacker-supplied data (the latter consistent with the CVSS integrity rating).

4. Post-exploitation impact. The attacker harvests the information disclosed through the broken-trust channel — content within the scope of the My Notes feature as exchanged over that connection. The confidentiality impact is rated High (C:H) and the integrity impact High (I:H) in the CVSS vector; availability is not impacted (A:N). Effects are scoped to the affected client component (S:U). No evidence of wormable, lateral, or pre-authentication remote code execution is present in the available data, and none should be assumed.

Defensive note: the absence of public exploit code and a Nuclei template lowers mass-scanning risk but does not reduce the targeted-attacker risk, because the technique (intercepting and mis-validating TLS) is a well-established adversary-in-the-middle pattern.

Impact Assessment

Business impact centers on confidentiality loss within the My Notes data stream. For enterprise Zoom deployments, the affected clients may be corporate-managed on endpoints that also carry meetings, chat metadata, and other note-bearing content. An information-disclosure flaw in a client trust path is especially concerning for regulated environments (financial, healthcare, legal) where note content may contain sensitive operational or client information. The High integrity subscore (I:H) also implies an attacker could feed manipulated data into the client under the guise of the trusted service, which could influence downstream workflows that consume My Notes content.

Blast radius is constrained on two axes. First, the CVSS attack complexity is High (AC:H), so exploitation is not opportunistic or drive-by; it requires the attacker to achieve a specific network position, which limits the population of realistic attackers. Scope is Unchanged (S:U), so impact is contained to the vulnerable client component rather than a separate authority or broad channel. There is no availability impact (A:N), so this is not a denial-of-service threat. Nevertheless, because no privileges (PR:N) and no user interaction (UI:N) are required, a well-positioned attacker can operate silently and at scale against many client instances whose traffic traverses the same compromised path (for example, a hostile or compromised network segment). The lack of a published affected-version range complicates asset inventory and prioritization, and the total absence of a patch (0/4 patch confidence) means exposure persists until the vendor issues a fix.

Detection Guidance

Sigma Rule

title: Zoom Client Improper Certificate Validation and My Notes Trust Abuse
id: 8f4c1b2e-3d57-4a90-9c11-7b6e2f0a4d21
status: experimental
description: Detects TLS/certificate validation failure indicators and AiTM patterns associated with Zoom My Notes improper certificate validation (CVE-2026-108185, CWE-295).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-108185
author: valtersit.com
date: 2026/01/01
tags:
  - attack.t1557
  - attack.credential_access
  - cwe.295
logsource:
  category: process_creation
  product: windows
detection:
  selection_zoom:
    Image|endswith:
      - '\Zoom.exe'
      - '\ZoomOutlookIMPlugin.exe'
  selection_tls_failure_strings:
    - 'certificate verify failed'
    - 'unable to verify'
    - 'SSL certificate problem'
    - 'self signed certificate'
    - 'hostname mismatch'
  condition: selection_zoom and selection_tls_failure_strings
falsepositives:
  - Legitimate TLS interception by corporate proxies using trusted internal CAs
  - Expired or misconfigured certificates on legitimate Zoom infrastructure
level: medium

YARA Rule

rule CVE_2026_108185_Zoom_MyNotes_TrustFail
{
    meta:
        description = "Detects client binaries/strings referencing Zoom My Notes and TLS verification bypass related to CVE-2026-108185 (CWE-295 improper certificate validation)"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-108185"
        date = "2026-01-01"
        cve = "CVE-2026-108185"
        cwe = "CWE-295"

    strings:
        $zoom = "Zoom" ascii wide nocase
        $notes1 = "My Notes" ascii wide nocase
        $notes2 = "mynotes" ascii wide nocase
        $tls1 = "SSL_VERIFY_NONE" ascii wide
        $tls2 = "verify_peer" ascii wide nocase
        $tls3 = "setVerify" ascii wide
        $tls4 = "X509_V_ERR" ascii wide
        $tls5 = "certificate verify failed" ascii wide nocase

    condition:
        $zoom and any of ($notes*) and 2 of ($tls*)
}

Suricata IDS Rule

alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-108185 Zoom Client TLS to Untrusted Certificate on My Notes Channel"; flow:established,to_server; tls.store; ssl_state:client_hello; threshold:type both,track by_src,count 5,seconds 60; classtype:policy-violation; reference:cve,2026-108185; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-108185; metadata:mitre_tactic T1557, cwe CWE-295; sid:2026108185; rev:1;)

alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-108185 Zoom Client Accepting Self-Signed/Invalid Certificate (My Notes)"; flow:established,to_client; tls.cert_subject; content:"CN="; pcre:"/CN=(?!.*zoom\.us|.*zoom\.com)/iR"; classtype:policy-violation; reference:cve,2026-108185; metadata:cwe CWE-295; sid:2026108186; rev:1;)

Note: Suricata rule is heuristic. TLS certificate anomalies must be correlated with Zoom client process/host context for accurate triage; the rule above will generate false positives against any non-Zoom TLS subject because certificate-subject matching cannot by itself identify which process negotiated the connection.

Elastic Detection

sequence by host.id with maxspan=5m
  [ process where process.name : ("Zoom.exe", "zoom.us", "ZoomOutlookIMPlugin.exe") ]
  [ network where network.protocol == "tls" and
      (tls.server.certificate_validation : "failed" or
       tls.server.certificate_issuer : null or
       tls.server.x509.not_before > tls.server.x509.not_after) ]

Splunk SPL Query

index=proxy OR index=network OR index=tls
(process_name="Zoom.exe" OR process_name="zoom.us" OR app="Zoom")
(ssl_certificate_validation="failed" OR ssl_certificate_issuer="self-signed" OR ssl_error="*certificate*verify*" OR ssl_x509_subject!=*zoom*)
| stats count min(_time) as first_seen max(_time) as last_seen values(dest) as destination values(ssl_x509_subject) as subject by src, process_name
| where count > 1
| sort - count

Wazuh OSSEC Rule

<group name="zoom,cve_2026_108185,cwe_295,">
  <rule id="1081850" level="10">
    <if_sid>5100</if_sid>
    <field name="win.eventdata.image">Zoom.exe|zoom.us|ZoomOutlookIMPlugin.exe</field>
    <match>TLS|SSL|certificate|My Notes|verify failed</match>
    <description>CVE-2026-108185: Zoom Client improper certificate validation (CWE-295) - potential My Notes information disclosure via invalid/untrusted TLS certificate</description>
    <mitre>
      <id>T1557</id>
    </mitre>
    <group>cwe_295,zoom,mitm,</group>
  </rule>
</group>

Note: Tune the <if_sid> base rule ID to match the event channel used in your deployment (e.g., Sysmon or Windows Security); the base ID above is a placeholder for an existing parent rule in a default Wazuh install and must be validated against your rule set.

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix, no workaround, and no affected-version range are available. Because no patch exists, mitigation is entirely compensatory and must focus on removing or disrupting the network precondition the attack depends on.

1. Immediate mitigations

• Enforce TLS inspection with strict, correctly configured certificate validation at the network edge so that any client-side validation failure is caught server-side and unwanted connections are dropped. Note the caveat above: TLS inspection that itself uses untrusted certificates will generate false positives and, if poorly configured, can mask the very anomaly being detected.
• Restrict Zoom client egress via allow-listing to known-good Zoom service endpoints and pinned certificate names where feasible, so that traffic to attacker-influenced or impersonated endpoints is blocked.
• Harden network access on untrusted segments (public Wi-Fi, guest networks, branch links) — mandate the corporate VPN with certificate pinning, and monitor for DNS/name-resolution manipulation (spoofed DNS responses, rogue DHCP, ARP anomalies) that enables the network-position precondition.
• Deploy the detection signatures above to identify Zoom client processes accepting self-signed or invalid certificates, and alert on certificate-subject mismatches involving Zoom client hosts. Treat certificate-subject mismatch alerts as heuristics requiring host/process correlation.
• Set EDR policy to record and alert on failed TLS verification events from Zoom client processes.

2. Patch/upgrade steps

• There is no patch. Monitor Zoom's official security advisories and the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-108185) for an affected-version statement and a fixed release.
• Maintain an accurate Zoom client inventory (desktop and plugin components such as the Outlook plugin) so that, once a fixed version is published, upgrade can be executed quickly across managed endpoints.
• Establish an out-of-band communication channel for the eventual vendor advisory so patch-response is not delayed by incomplete initial information.

3. Long-term hardening

• Institute a software supply-chain/vulnerability SLAs that trigger expedited handling for unauthenticated, no-interaction, network-reachable CVEs (PR:N/UI:N/AV:N) even when attack complexity is High, since such defects are attractive to positioned adversaries.
• Adopt certificate pinning and/or strict hostname verification requirements for first-party client applications, and validate that third-party client code (features such as My Notes) meets the same TLS-validation standard.
• Improve network monitoring coverage for TLS certificate anomalies (issuer, subject, validity window, self-signed) correlated with client process telemetry, and add allow-listing for all known Zoom service endpoints.
• Require regular client updates and enforce a baseline that disables or restricts high-risk client features until patched, where operationally feasible.

References

• NVD — CVE-2026-108185: https://nvd.nist.gov/vuln/detail/CVE-2026-108185
• CWE-295: Improper Certificate Validation — https://cwe.mitre.org/data/definitions/295.html
• Zoom Security Bulletins (vendor advisory page; no CVE-specific bulletin confirmed at time of writing): https://explore.zoom.us/en/trust/security/security-bulletin/
• CISA Known Exploited Vulnerabilities Catalog (CVE-2026-108185 not listed as of this report): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• MITRE ATT&CK T1557 — Adversary-in-the-Middle: https://attack.mitre.org/techniques/T1557/

Exploit-in-the-wild evidence: none. No public PoC, no exploit code, no Nuclei template, and no CISA KEV listing. No named threat-actor campaign is associated with this CVE in any tracked source.