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CVE-2026-48164— Collabora Online: Reflected HTML injection through host_session_id

Quick assessment

Affected
CollaboraOnline online
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.

Collabora Online 是一款基于 LibreOffice 技术的在线协同办公套件。在 24.04.18 和 25.04.11 版本之前， 查询/表单参数会被直接插入到 编辑器页面中，且未经过 HTML 编码，这与通过现有变量编码机制传递的参数处理方式不同。攻击者若诱导受害者加载恶意构造的 URL，即可注入 HTML 内容；若未配置有效的内容安全策略（Content Security Policy, CSP），攻击者便能在 Collabora Online 的 iframe 所属源中执行脚本，从而窃取会话

CVSS 4.7 · Medium
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I. Basic Information for CVE-2026-48164

Vulnerability Information
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Vulnerability Title
Collabora Online: Reflected HTML injection through host_session_id
Source: CVE Program / CVE List V5
Vulnerability Description
Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the `host_session_id` query/form parameter is substituted into the `cool.html` editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective `Content Security Policy`, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the `Content Security Policy` header sent by `coolwsd` mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
CollaboraOnline online < 24.04.18 -

II. Public POCs for CVE-2026-48164

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III. Intelligence Information for CVE-2026-48164

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Other References for CVE-2026-48164 (2)

IV. Related Vulnerabilities

Same product: online
Same vendor: CollaboraOnline
Same weakness: CWE-79