CVE-2021-27279 : MyBB before 1.8.25 allows stored XSS via nested [email] tags with MyCode (aka BB

MyBB before 1.8.25 allows stored XSS via nested [email] tags with MyCode (aka BBCode).

Published 2021-02-22 20:15:13

Updated 2021-02-26 15:37:45

Source MITRE

View at NVD, CVE.org

Vulnerability category: Cross site scripting (XSS)

Products affected by CVE-2021-27279

Mybb » Mybb
Versions before (<) 1.8.25
cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:*
Matching versions

EPSS FAQ

0.06%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 24 %

Percentile, the proportion of vulnerabilities that are scored at or less

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
3.5	LOW	AV:N/AC:M/Au:S/C:N/I:P/A:N	6.8	2.9	NIST
Access Vector: Network Access Complexity: Medium Authentication: Single Confidentiality Impact: None Integrity Impact: Partial Availability Impact: None
5.4	MEDIUM	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N	2.3	2.7	NIST
Attack Vector: Network Attack Complexity: Low Privileges Required: Low User Interaction: Required Scope: Changed Confidentiality: Low Integrity: Low Availability: None

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Assigned by: nvd@nist.gov (Primary)

https://mybb.com/versions/1.8.25/

Version 1.8.25 - MyBB
Release Notes;Vendor Advisory
https://github.com/mybb/mybb/commit/cb781b49116bf5c4d8deca3e17498122b701677a

Fix Nested Email MyCode Persistent XSS · mybb/mybb@cb781b4 · GitHub
Patch;Third Party Advisory
https://github.com/mybb/mybb/security/advisories/GHSA-6483-hcpp-p75w

Nested Email MyCode Persistent XSS · Advisory · mybb/mybb · GitHub
Exploit;Third Party Advisory

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