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CVE-2026-103858— MISP Incomplete Thread Authorization Allows Unauthorized Read and Post Access to Discussions

Quick assessment

Affected
MISP MISP
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.

MISP 在讨论发帖功能中存在不完整的授权检查漏洞。当用户向某个线程提交帖子或回复现有帖子时，应用程序仅验证了目标线程是否被限制为单一组织（org-only 分发级别），而未强制执行完整的线程访问控制列表，包括共享组成员资格和事件级别的可见性权限。 因此，一个已认证但不在相关共享组中、或对关联事件没有可见性权限的用户可以： 读取线程标题以及被引用帖子的内容 向该讨论线程提交新的帖子 这既构成了信息泄露（读取受限的线程和帖子内容），也构成完整性问题（向用户无权参与的线程注入内容）。 受影响版本：< 2.5.48

CVSS 5.3 · Medium EPSS 0.22% · P11

Possible ATT&CK Techniques 2 AI

T1566 · Phishing T1078 · Valid Accounts

Affected Version Matrix 1

VendorProduct Version RangeStatus
MISP MISP unspecified< 2.5.48 affected
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I. Basic Information for CVE-2026-103858

Vulnerability Information
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Vulnerability Title
MISP Incomplete Thread Authorization Allows Unauthorized Read and Post Access to Discussions
Source: CVE Program / CVE List V5
Vulnerability Description
MISP contains an incomplete authorization check in the discussion posting functionality. When a user submits a post to a thread or replies to an existing post, the application only verified whether the target thread was restricted to a single organization (org-only distribution). It did not enforce the full thread access control list, including sharing-group membership and event-level visibility. As a result, an authenticated user who is outside the relevant sharing group or who does not have visibility on the associated event could: - Read the thread title and the content of the quoted post - Submit a new post into the discussion thread This constitutes both an information disclosure (reading restricted thread and post content) and an integrity issue (injecting content into a thread the user is not authorized to participate in). Affected: <2.5.48
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
MISP MISP unspecified ~ 2.5.48 cpe:2.3:a:misp:misp:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-103858

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III. Intelligence Information for CVE-2026-103858

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Patches & Fixes for CVE-2026-103858 (1)

Same Patch Batch · MISP · 2026-10-01 · 6 CVEs total

CVE-2026-103655 9.3 CRITICAL MISP TOTP Code Replay Allows Duplicate Authentication Within Validity Period
CVE-2026-103651 7.6 HIGH MISP HOTP Token Replay via Stale Session-Cached Counter Allows Second-Factor Authenticatio
CVE-2026-103659 7.1 HIGH MISP: Object Distribution ACL Bypass via Event Flattening Exposes Organisation-Only Attrib
CVE-2026-103662 5.1 MEDIUM MISP Reflected XSS in Taxonomy Tag Confirmation Forms
CVE-2026-103664 4.8 MEDIUM MISP Reflected Cross-Site Scripting via Unsanitized Analyst Data Seed Parameter

IV. Related Vulnerabilities

Same product: MISP
Same vendor: MISP
Same weakness: CWE-285

V. Comments for CVE-2026-103858

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