Memory Overread in Citrix NetScaler Gateway
CVE-2025-5777 Published on June 17, 2025
NetScaler ADC and NetScaler Gateway - Insufficient input validation leading to memory overread
Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
Known Exploited Vulnerability
This Citrix NetScaler ADC and Gateway Out-of-Bounds Read Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Citrix NetScaler ADC and Gateway contain an out-of-bounds read vulnerability due to insufficient input validation. This vulnerability can lead to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.
The following remediation steps are recommended / required by July 11, 2025: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Weakness Types
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Use of Uninitialized Variable
The code uses a variable that has not been initialized, leading to unpredictable or unintended results. In some languages such as C and C++, stack variables are not initialized by default. They generally contain junk data with the contents of stack memory before the function was invoked. An attacker can sometimes control or read these contents. In other languages or conditions, a variable that is not explicitly initialized can be given a default value that has security implications, depending on the logic of the program. The presence of an uninitialized variable can sometimes indicate a typographic error in the code.
Products Associated with CVE-2025-5777
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Affected Versions
NetScaler ADC:- Version 14.1 and below 43.56 is affected.
- Version 13.1 and below 58.32 is affected.
- Version 14.1 and below 43.56 is affected.
- Version 13.1 and below 58.32 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.