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CVE-2026-47245— MyBB: Buddy list corruption

Quick assessment

Affected
mybb mybb
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.

MyBB是MyBB组织开源的一套用PHP和MySQL开发的免费且基于Web的论坛软件。该软件具有简单易用、支持多国语言、可扩展等特点。 MyBB 1.8.40之前版本存在异常处理不当漏洞，该漏洞源于User CP Buddy/Ignore List组件未正确验证互惠好友列表更新，删除处理程序使用未检查的array_search()返回值作为数组键，可能导致移除目标账户的第一个存储好友。

CVSS 4.3 · Medium EPSS 0.27% · P19

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
mybb mybb < 1.8.40 affected
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I. Basic Information for CVE-2026-47245

Vulnerability Information
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Vulnerability Title
MyBB: Buddy list corruption
Source: CVE Program / CVE List V5
Vulnerability Description
MyBB is free and open source forum software. Prior to 1.8.40, the User CP Buddy/Ignore List component does not validate reciprocal buddy-list updates correctly. The usercp.php?action=do_editlists delete handler removes the selected entry from the acting user's list and then updates mybb_users.buddylist for the target account. The reciprocal update searches for the deleted target UID instead of the acting user's UID and uses the unchecked array_search() return value as an array key. A false result can be converted to index 0, removing the target account's first stored buddy while leaving the actual reciprocal entry unchanged. The uniquely identifying implementation details include false converted to index 0. This issue is fixed in version 1.8.40.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
未加检查的返回值
Source: CVE Program / CVE List V5
Vulnerability Title
MyBB 异常处理不当漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MyBB是MyBB组织开源的一套用PHP和MySQL开发的免费且基于Web的论坛软件。该软件具有简单易用、支持多国语言、可扩展等特点。 MyBB 1.8.40之前版本存在异常处理不当漏洞，该漏洞源于User CP Buddy/Ignore List组件未正确验证互惠好友列表更新，删除处理程序使用未检查的array_search()返回值作为数组键，可能导致移除目标账户的第一个存储好友。
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
mybb mybb < 1.8.40 -

II. Public POCs for CVE-2026-47245

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III. Intelligence Information for CVE-2026-47245

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Patches & Fixes for CVE-2026-47245 (2)

Vendor Advisories for CVE-2026-47245 (1)

Vendor Pages for CVE-2026-47245 (1)

Same Patch Batch · mybb · 2026-08-18 · 18 CVEs total

CVE-2026-45117 9.8 CRITICAL MyBB: Installer database configuration RCE
CVE-2026-45118 9.3 CRITICAL MyBB: Contact page reflected XSS
CVE-2026-45115 8.7 HIGH MyBB: Buddy/ignore list username XSS
CVE-2026-45116 8.7 HIGH MyBB: Profile field type confusion XSS
CVE-2026-45120 5.4 MEDIUM MyBB: Insufficient authorization for private calendar events
CVE-2026-46482 5.3 MEDIUM MyBB: Security Question insufficient validation
CVE-2026-45734 5.3 MEDIUM MyBB: Default CAPTCHA missing invalidation
CVE-2026-45125 5.3 MEDIUM MyBB: Email User CRLF injection
CVE-2026-45119 4.6 MEDIUM MyBB: ACP UTF-8 Conversion CSRF
CVE-2026-45129 4.6 MEDIUM MyBB: ACP Recovery Codes CSRF
CVE-2026-45123 4.3 MEDIUM MyBB: IPv6 SSRF
CVE-2026-45122 4.3 MEDIUM MyBB: Insufficient permission check for calendar event move
CVE-2026-45121 4.3 MEDIUM MyBB: Insufficient permission check for calendar select
CVE-2026-45124 4.3 MEDIUM MyBB: Mod CP report resolution missing authorization
CVE-2026-45126 3.5 LOW MyBB: ACP Questions state CSRF
CVE-2026-45128 3.5 LOW MyBB: ACP Users View Manager default CSRF
CVE-2026-45127 3.5 LOW MyBB: ACP Mass Mail draft resend CSRF

IV. Related Vulnerabilities

Same product: mybb
Same vendor: mybb
Same weakness: CWE-252

V. Comments for CVE-2026-47245

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