CVE-2026-2578— Information Disclosure via WebSocket Event When Deleting Unrevealed Burn on Read Posts
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 11.3.0及之前的11.3.x版本存在安全漏洞，该漏洞源于在删除期间未能保留阅后即焚帖子的编辑状态，可能导致频道成员通过WebSocket帖子删除事件访问未揭示的阅后即焚消息内容。
Possible ATT&CK Techniques 1 AI
T1530 · Data from Cloud Storage
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I. Basic Information for CVE-2026-2578
Vulnerability Information
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Vulnerability Title
Information Disclosure via WebSocket Event When Deleting Unrevealed Burn on Read Posts
Source: CVE Program / CVE List V5
Vulnerability Description
Mattermost versions 11.3.x <= 11.3.0 fail to preserve the redacted state of burn-on-read posts during deletion which allows channel members to access unrevealed burn-on-read message contents via the WebSocket post deletion event.. Mattermost Advisory ID: MMSA-2026-00579
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过发送数据的信息暴露
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 11.3.0及之前的11.3.x版本存在安全漏洞，该漏洞源于在删除期间未能保留阅后即焚帖子的编辑状态，可能导致频道成员通过WebSocket帖子删除事件访问未揭示的阅后即焚消息内容。
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 | 11.3.0 ~ 11.3.0 | - |
|
II. Public POCs for CVE-2026-2578
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Mattermost · 2026-03-16 · 21 CVEs total
| CVE-2026-2476 | 7.6 HIGH | MS Teams plugin sensitive config values not properly masked in support packets |
| CVE-2026-24458 | 7.5 HIGH | DoS attack via login attempts with multi-megabyte passwords |
| CVE-2026-2462 | 6.6 MEDIUM | Admin RCE via Malicious Plugin Upload on CI Test Instances |
| CVE-2026-2454 | 5.8 MEDIUM | DoS in Calls plugin via malformed msgpack in websocket request. |
| CVE-2026-2456 | 5.3 MEDIUM | Denial of Service via Unbounded Memory Allocation in Integration Actions |
| CVE-2026-25783 | 4.3 MEDIUM | Denial of service via malformed User-Agent header in getBrowserVersion |
| CVE-2026-2463 | 4.3 MEDIUM | Unauthorized access to invite ID during team creation |
| CVE-2026-2461 | 4.3 MEDIUM | Missing authorization check allows unauthorized modification of other users' comments on a |
| CVE-2026-2457 | 4.3 MEDIUM | WebSocket Message Spoofing via Permalink Embed Manipulation |
| CVE-2026-2458 | 4.3 MEDIUM | Unauthorized channel enumeration in private teams after member removal |
| CVE-2026-26246 | 4.3 MEDIUM | Memory Exhaustion via Malformed PSD File Upload |
| CVE-2026-1629 | 4.3 MEDIUM | Permalink Preview Information Disclosure After Permission Revocation |
| CVE-2026-4265 | 4.3 MEDIUM | Guest user can upload files without permission across teams |
| CVE-2026-25780 | 4.3 MEDIUM | Memory Exhaustion via Malformed DOC File Upload |
| CVE-2026-21386 | 4.3 MEDIUM | Private channel enumeration via /mute slash command |
| CVE-2026-2455 | 4.3 MEDIUM | SSRF bypass via IPv4-mapped IPv6 literals |
| CVE-2026-24692 | 4.3 MEDIUM | Guest users can bypass read permissions via search API |
| CVE-2026-26304 | 4.3 MEDIUM | Permission Bypass in Playbook Run Creation |
| CVE-2026-26230 | 3.8 LOW | Team Admin Privilege Escalation to Demote Members to Guest |
| CVE-2026-22545 | 3.1 LOW | Password Change Bypass via Auth Switch Endpoint |
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V. Comments for CVE-2026-2578
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