Fortinet patches FortiSandbox XSS flaw
Fortinet fixed a cross-site scripting vulnerability in FortiSandbox that could let attackers hijack user sessions via crafted links.
Sourceadvisories.ncsc.nl — open the original
What to check
- Applies to
- The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
NCSC-NL published an advisory describing a cross-site scripting (XSS) vulnerability in multiple versions of Fortinet FortiSandbox, tracked as CVE-2026-26248 with a CVSS v3 score of 8.8. The flaw stems from improper neutralization of input during web page generation, allowing an unauthenticated attacker to craft malicious HTTP requests and, through social engineering, lure a user into opening a malicious link or page. Successful exploitation results in execution of arbitrary JavaScript in the context of the web application, potentially leading to unauthorized actions on behalf of the user, session compromise, or data integrity issues.
Fortinet has released updates to address the vulnerability. The advisory does not indicate any evidence of active exploitation in the wild. Defenders operating FortiSandbox should apply the vendor-supplied patches promptly and review user-facing web interfaces for unusual script execution or session anomalies, particularly where users may be targeted via phishing-style links referencing the FortiSandbox interface.
Mentioned in this report
Source reporting: https://advisories.ncsc.nl/2026/ncsc-2026-0483.html
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