Fortra Cobalt Strike Teamserver Cross-Site Scripting (XSS) Vulnerability
An XSS (Cross Site Scripting) vulnerability was found in HelpSystems Cobalt Strike through 4.7 that allowed a remote attacker to execute HTML on the Cobalt Strike teamserver. To exploit the vulnerability, one must first inspect a Cobalt…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 4 / 5
- KEV catalog (CISA)30 Mar 2023
- Exploited in EUVD (ENISA)30 Mar 2023
- Used by ransomwareno
- EPSS above 10 %44.1%
- No account, over the networkyes
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: Apply updates per vendor instructions.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
An XSS (Cross Site Scripting) vulnerability was found in HelpSystems Cobalt Strike through 4.7 that allowed a remote attacker to execute HTML on the Cobalt Strike teamserver. To exploit the vulnerability, one must first inspect a Cobalt Strike payload, and then modify the username field in the payload (or create a new payload with the extracted information and then modify that username field to be malformed).
Affected products
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
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EPSS peak: 47.9%
References
Other exploited vulnerabilities from the same vendor
- CVE-2025-10035Fortra GoAnywhere MFT Deserialization of Untrusted Data Vulnerability10.0 · Background exploitation
- CVE-2022-42948Fortra Cobalt Strike User Interface Remote Code Execution Vulnerability5.8 · Background exploitation
- CVE-2023-0669Fortra GoAnywhere MFT Remote Code Execution Vulnerability8.3 · Background exploitation