CVE-2026-20719— DoS via URL Previews Rendering Malicious SVGs
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I. Basic Information for CVE-2026-20719
Vulnerability Information
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Vulnerability Title
DoS via URL Previews Rendering Malicious SVGs
Source: NVD (National Vulnerability Database)
Vulnerability Description
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via creating an issue or PR on GitHub.. Mattermost Advisory ID: MMSA-2026-00595
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
对因果或异常条件的不恰当检查
Source: NVD (National Vulnerability Database)
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 11.4.0及之前的11.4.x版本、11.3.1及之前的11.3.x版本、11.2.3及之前的11.2.x版本和10.11.11及之前的10.11.x版本存在安全漏洞，该漏洞源于未能阻止链接嵌入中外部SVG的渲染，可能导致未经验证的用户通过创建GitHub问题或PR使Mattermost Web应用和桌面应用崩溃。
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 | 11.4.0 ~ 11.4.0 | - |
II. Public POCs for CVE-2026-20719
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Mattermost · 2026-03-25 · 4 CVEs total
| CVE-2026-27656 | 5.7 MEDIUM | Account Takeover via Substring Matching in OpenID Connect Authentication |
| CVE-2026-27659 | 4.6 MEDIUM | CSRF vulnerability in UpdateAccessControlPolicyActiveStatus endpoint |
| CVE-2026-26233 | 4.3 MEDIUM | Denial of Service via HTTP/2 single packet attack on login endpoint |
IV. Related Vulnerabilities
Same product: Mattermost
- CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Tok - CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authenticati - CVE-2026-27769
Connected Workspaces: Malicious remote server can manipulate - CVE-2026-24661
Unbounded Request Body Read in MS Teams Plugin {{/changes}} - CVE-2026-21388
Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}
Same vendor: Mattermost
- CVE-2026-3590
Race Condition in Guest Magic Link Authentication Allows Tok - CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authenticati - CVE-2026-27769
Connected Workspaces: Malicious remote server can manipulate - CVE-2026-24661
Unbounded Request Body Read in MS Teams Plugin {{/changes}} - CVE-2026-21388
Unbounded Request Body Read in MS Teams Plugin {{/lifecycle}
Same weakness: CWE-754
- CVE-2026-41662
Admidio: Missing Minimum Administrator Check in Role Members - CVE-2026-35225
Improper timeout handling in CODESYS EtherNetIP - CVE-2026-35366
uutils coreutils printenv Security Inspection Bypass via UTF - CVE-2026-40343
free5GC UDR: Fail-open handling in PolicyDataSubsToNotifyPos - CVE-2026-40249
free5gc UDR fail-open request handling in PolicyDataSubsToNo
V. Comments for CVE-2026-20719
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