CVE-2026-3055
Citrix NetScaler Out-of-Bounds Read Vulnerability
Citrix NetScaler
Insufficient input validation in NetScaler ADC and NetScaler Gateway when configured as a SAML IDP leading to memory overread
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 30 March 2026. US federal agencies were required to remediate it by 2 April 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 91.5%, which is higher than 99.8% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2026-3055 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-3055.
What does CVE-2026-3055 affect?
CVE-2026-3055 affects Citrix NetScaler. Insufficient input validation in NetScaler ADC and NetScaler Gateway when configured as a SAML IDP leading to memory overread
How severe is CVE-2026-3055?
CVE-2026-3055 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 91.5%, higher than 99.8% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 2 April 2026.
How should organisations respond to CVE-2026-3055?
Apply the vendor patch for Citrix NetScaler as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.