CVE-2026-88777 in ADC
Summary
by MITRE • 09/27/2026
Memory overflow vulnerability vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway.
This issue affects ADC: before 14.1-73.37, before 13.1-64.23, before 14.1-73.37 FIPS, and before 13.1.37.279 FIPS and NDcPP; Gateway: before 14.1-73.37 and before 13.1-64.23 leading to unpredictable or erroneous behavior or Denial of Service
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Analysis
by VulDB Data Team • 09/27/2026
The identified vulnerability represents a critical memory overflow condition within the core processing components of Citrix NetScaler ADC and Citrix NetScaler Gateway appliances. This flaw is present in specific legacy versions, including all releases prior to 14.1-73.37 for both ADC and Gateway platforms, as well as earlier builds such as 13.1-64.23 and the FIPS-compliant variants like 14.1-73.37 FIPS and 13.1.37.279 NDcPP. The root cause of this issue lies in improper handling of memory allocation or boundary checks during the processing of specific input data streams, which allows an attacker to write beyond the allocated buffer limits. This type of defect is classically categorized under CWE-120 Buffer Overflow and often involves CWE-401 Missing Release of Memory after Effective Lifetime if it leads to resource exhaustion over time, though in this context, the immediate risk is stack or heap corruption due to excessive data ingestion.
From a technical perspective, memory overflow vulnerabilities are particularly dangerous because they can lead to arbitrary code execution if exploited with shellcode injection techniques, although the primary reported impact here focuses on system stability and availability. When an attacker sends crafted requests that trigger this buffer over-read or over-write condition, the internal state of the NetScaler process becomes corrupted. This corruption disrupts normal operation flows, causing the application layer to behave unpredictably. The immediate operational consequence is a Denial of Service, where the affected service crashes or hangs, rendering it unable to serve legitimate user traffic. In high-availability deployments, this can lead to failover events and potential data loss if state synchronization is interrupted during the crash sequence.
The impact extends beyond simple service interruption. Because NetScaler ADC and Gateway often sit at the edge of enterprise networks acting as reverse proxies and load balancers, a compromise or disruption here affects all downstream applications protected by these devices. An attacker could potentially leverage this vulnerability to perform reconnaissance if the error messages expose internal stack traces or memory addresses, which would aid in further exploitation attempts targeting other components within the infrastructure. Furthermore, repeated triggering of this flaw can lead to resource exhaustion on the appliance itself, consuming CPU cycles and memory as the system attempts to recover from errors, thereby degrading performance for all connected clients even if a full crash does not occur immediately.
Mitigation strategies must prioritize immediate patching to eliminate the attack surface associated with these specific version numbers. Administrators should upgrade Citrix NetScaler ADC and Gateway to versions 14.1-73.37 or later, and 13.1-64.23 or later respectively, ensuring that FIPS and NDcPP compliant builds are also updated to their corresponding secure baselines. In environments where immediate patching is not feasible due to maintenance windows or compatibility concerns with downstream applications, network-level mitigations should be implemented. This includes configuring strict rate limiting on incoming connections to prevent rapid-fire exploitation attempts and deploying Web Application Firewall rules that inspect for anomalous packet sizes or malformed headers indicative of buffer overflow attacks. Additionally, enabling comprehensive logging and monitoring allows security operations teams to detect spikes in error rates or connection drops that may signal an active exploitation attempt against this vulnerability.
From a threat intelligence perspective, this vulnerability aligns with ATT&CK technique T1498 Network Denial of Service, as the primary outcome is the disruption of service availability rather than data exfiltration at this stage. However, given the nature of memory corruption flaws, there remains a latent risk that could be chained with other vulnerabilities to achieve privilege escalation or remote code execution, similar to patterns observed in ATT&CK technique T1068 Exploitation for Privilege Escalation if local access were somehow gained through auxiliary means. Therefore, treating this issue as high severity is warranted not only for its immediate denial-of-service potential but also because memory corruption flaws are frequently precursors to more severe compromises in complex software stacks like NetScaler. Continuous monitoring of vendor advisories and regular vulnerability scanning against known CVE databases remain essential practices for maintaining the integrity of these critical network infrastructure components.