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CVE-2021-43991

Persistent XSS via Avatar Upload in Kentico Xperience CMS

6.8 Medium

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.56%Up 0.1 points since Dec 4, 2021
90%50%10%1%

What each source reports

CVE List Score used 6.8

Persistent XSS via Avatar Upload in Kentico Xperience CMS

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data.

Record
CVE-2021-43991
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2021-30852 6.8

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data.

Record
EUVD-2021-30852
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-r763-2x4q-j7xx No score

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site...

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data.

Record
GHSA-r763-2x4q-j7xx
Weakness
CWE-79
Updated
2026-11-02
NVD 6.8

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data.

Record
CVE-2021-43991
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0
3.5 LowAV:N/AC:M/Au:S/C:N/I:P/A:N
Weakness
CWE-79
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-43991 is a medium vulnerability (CVSS 6.8) in Kentico Xperience, published December 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.56%, the 47th percentile. No source names a fixed version.

References

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