CVE-2026-3109— Missing timestamp validation in Zoom webhook handler
Quick assessment
Affected
Mattermost Mattermost
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 11.4 10.11.11.0及之前版本存在安全漏洞，该漏洞源于未验证Webhook请求时间戳，可能导致通过重放请求破坏Zoom会议状态。
Possible ATT&CK Techniques 2 AI
T1539 · Steal Web Session Cookie T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-3109
Vulnerability Information
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Vulnerability Title
Missing timestamp validation in Zoom webhook handler
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost Plugins versions <=11.4 10.11.11.0 fail to validate webhook request timestamps which allows an attacker to corrupt Zoom meeting state in Mattermost via replayed webhook requests. Mattermost Advisory ID: MMSA-2026-00584
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
对因果或异常条件的不恰当检查
Source: CVE Program / CVE List V5
Vulnerability Title
Mattermost 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 11.4 10.11.11.0及之前版本存在安全漏洞，该漏洞源于未验证Webhook请求时间戳，可能导致通过重放请求破坏Zoom会议状态。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Mattermost | Mattermost | 0 ~ 10.11.11 | - |
|
II. Public POCs for CVE-2026-3109
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Same Patch Batch · Mattermost · 2026-03-26 · 8 CVEs total
| CVE-2026-3108 | 8.0 HIGH | Terminal Escape Injection in mmctl Report Posts Command |
| CVE-2026-3112 | 6.8 MEDIUM | Arbitrary File Read via Advanced Logging Support Packet |
| CVE-2026-3114 | 6.5 MEDIUM | Zip Bomb Denial of Service via Unrestricted Archive Decompression |
| CVE-2026-4274 | 5.4 MEDIUM | Insufficient authorization in shared channel membership sync grants team-level access inst |
| CVE-2026-3113 | 5.0 MEDIUM | mmctl export download command doesn’t restrict permissions to created file to file owner |
| CVE-2026-3116 | 4.9 MEDIUM | Improper Input Validation in Zoom Plugin Webhook Handler |
| CVE-2026-3115 | 4.3 MEDIUM | Guest users can view group member IDs without respecting view restrictions |
IV. Related Vulnerabilities
Same product: Mattermost
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CVE-2026-18799
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CVE-2026-16251
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CVE-2026-18256
Private team metadata disclosure via the team search API -
CVE-2026-18223
Mattermost invitation tokens not bound to invited email addr -
CVE-2026-19076
Mattermost fails to reject OAuth application sessions in acc
Same vendor: Mattermost
-
CVE-2026-18799
Mattermost Server fails to restrict Slack import account bin -
CVE-2026-16251
Mattermost local image proxy allows server memory exhaustion -
CVE-2026-18256
Private team metadata disclosure via the team search API -
CVE-2026-18223
Mattermost invitation tokens not bound to invited email addr -
CVE-2026-19076
Mattermost fails to reject OAuth application sessions in acc
Same weakness: CWE-754
V. Comments for CVE-2026-3109
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