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CVE-2026-63466— Unleash: Global Mustache.escape override disables HTML escaping process-wide, enabling Slack/Teams link-injection via unrestricted username

Quick assessment

Affected
Unleash unleash
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.

Unleash是Unleash组织的一款功能管理平台。 Unleash 8.0.3之前版本存在输出处理不当漏洞，该漏洞源于将Mustache.escape设置为恒等函数，导致后续Mustache.render调用未转义，可能允许编辑器级别用户在不受限制的用户名中放置Slack或Microsoft Teams链接语法，触发功能事件并将攻击者标记的链接注入可信外部通知渠道。

CVSS 4.1 · Medium EPSS 0.32% · P24

Possible ATT&CK Techniques 1 AI

T1556 · Modify Authentication Process

Affected Version Matrix 1

VendorProduct Version RangeStatus
Unleash unleash < 8.0.3 affected
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I. Basic Information for CVE-2026-63466

Vulnerability Information
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Vulnerability Title
Unleash: Global Mustache.escape override disables HTML escaping process-wide, enabling Slack/Teams link-injection via unrestricted username
Source: CVE Program / CVE List V5
Vulnerability Description
Unleash is an open-source feature management platform. Prior to 8.0.3, FeatureEventFormatterMd.format in src/lib/addons/feature-event-formatter-md.ts assigns Mustache.escape to an identity function before rendering action and path templates. Because Mustache.escape is process-wide, the assignment disables escaping for subsequent Mustache.render calls in email-service.ts, webhook.ts, datadog.ts, and new-relic.ts. An editor-level user can place Slack or Microsoft Teams link syntax in an unrestricted username, trigger a feature event, and inject an attacker-labeled link into a trusted outbound notification channel, while other Mustache sinks remain unescaped until restart. This issue is fixed in version 8.0.3.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对输出编码和转义不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Unleash 输出处理不当漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Unleash是Unleash组织的一款功能管理平台。 Unleash 8.0.3之前版本存在输出处理不当漏洞，该漏洞源于将Mustache.escape设置为恒等函数，导致后续Mustache.render调用未转义，可能允许编辑器级别用户在不受限制的用户名中放置Slack或Microsoft Teams链接语法，触发功能事件并将攻击者标记的链接注入可信外部通知渠道。
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
Unleash unleash < 8.0.3 -

II. Public POCs for CVE-2026-63466

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III. Intelligence Information for CVE-2026-63466

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Patches & Fixes for CVE-2026-63466 (1)

Vendor Advisories for CVE-2026-63466 (1)

Other References for CVE-2026-63466 (1)

Same Patch Batch · Unleash · 2026-08-21 · 3 CVEs total

CVE-2026-63462 7.5 HIGH Unleash: Unauthenticated single-request DoS via OpenAPI validation error formatter
CVE-2026-63004 5.5 MEDIUM Unleash: Addon webhook URL is dialed server-side with no internal-address filtering, enabl

IV. Related Vulnerabilities

Same product: unleash
Same vendor: Unleash
Same weakness: CWE-116