CVE-2020-26768
Formstone Vulnerable to Reflected XSS
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
6.1
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
- Record
CVE-2020-26768- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:N/I:P/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
CVE List No score
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
- Record
CVE-2020-26768- Updated
- 2026-11-02
EUVDEUVD-2022-5546 No score
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
- Record
EUVD-2022-5546- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-wc29-h54q-q8qx
6.1
Formstone Vulnerable to Reflected XSS
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
- Record
GHSA-wc29-h54q-q8qx- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
6.1
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
- Record
CVE-2020-26768- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-wc29-h54q-q8qx
6.1
Formstone Vulnerable to Reflected XSS
Formstone <=1.4.16 is vulnerable to a Reflected Cross-Site Scripting (XSS) vulnerability caused by improper validation of user supplied input in the upload-target.php and upload-chunked.php files. A remote attacker could exploit this vulnerability using a specially crafted URL to execute a script in a victim's Web browser within the security context of the hosting Web site once the URL is clicked or visited. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials, force malware execution, user redirection and others.
- Record
GHSA-wc29-h54q-q8qx- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-26768 is a medium vulnerability (CVSS 6.1) in Formstone, published January 7, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.28%, the 70th percentile. Fixed in formstone 1.4.17.