Citrix NetScaler Out-of-Bounds Read (CVE-2026-3055)

Historical catalog analysis: CISA added this entry on March 30, 2026. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2026-3055 is an out-of-bounds read vulnerability (CWE-125) identified in several Citrix NetScaler products. According to CISA, this flaw can lead to a memory overread condition. The vulnerability was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on March 30, 2026.

Exposure and applicability

This vulnerability does not affect all NetScaler deployments. It is specifically applicable to systems configured as a SAML Identity Provider (IDP). The affected product lines include:

• NetScaler ADC (formerly Citrix ADC)
• NetScaler Gateway (formerly Citrix Gateway)
• NetScaler ADC FIPS
• NDcPP

Organizations that do not utilize these products in a SAML IDP configuration are not exposed to this specific memory overread flaw based on the provided source data.

Remediation priorities

Our analysis suggests prioritizing remediation based on the active exploitation signal indicated by its inclusion in the KEV catalog. The following actions are prioritized for vulnerability management teams:

1. Asset Identification: Immediately identify all NetScaler ADC and Gateway instances currently configured as SAML IDPs to determine the actual attack surface.
2. Vendor Mitigation Application: Apply mitigations according to official vendor instructions. For federal agencies, CISA has established a remediation deadline of April 2, 2026.
3. Service Evaluation: In scenarios where vendor mitigations are unavailable or cannot be applied, the source suggests discontinuing use of the product as a necessary step to eliminate exposure.

How to validate remediation

Verification must move beyond simply confirming a patch was deployed; it requires evidence that the specific exposure path is closed. We recommend the following validation steps:

• Version Correlation: Compare the current running firmware version against the fixed versions explicitly listed in the vendor’s security bulletin (CTX696300). A version check alone is a prerequisite, not proof of mitigation.
• Configuration Audit: For assets where patching is delayed, verify if the SAML IDP configuration has been disabled or removed, as this removes the condition required for the vulnerability to exist.

Limits and open questions

Several technical uncertainties remain based on the available source data:

• Exploitation Context: While listed in the KEV catalog, it is unknown if this vulnerability has been utilized by ransomware campaigns.
• Version Specifics: The source does not explicitly list the vulnerable or patched version numbers within the text; these must be retrieved from the referenced vendor bulletin.
• Residual Risk: It remains unclear if compensating controls (such as WAF rules) can effectively mitigate memory overread attempts without a formal patch, leaving a potential gap in defense for systems that cannot be immediately updated.

Source and editorial note

CVE-2026-3055: Citrix NetScaler Out-of-Bounds Read Vulnerability · Source date: March 30, 2026 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: April 02, 2026. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: September 02, 2026 at 00:52 UTC.

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