> ## Content Index > Fetch the complete content index at: https://f4n6.co.uk/llms.txt > Use this file to discover other available public pages before exploring further. # CVE-2026-88779 Citrix NetScaler: Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability - URL: https://f4n6.co.uk/security-feed/cve-2026-88779-citrix-netscaler-citrix-netscaler-improper-restriction-of-operations-within-the-bounds-of-a-memory-buffer-vulnerability/ - Published: 2026-10-04T20:27:59.000Z - Updated: 2026-10-04T20:27:59.000Z - Author: Jeff Davies - Tags: #security-feed, CVE-2026-88779 ## 1\. Executive summary CVE-2026-88779 is a memory-buffer flaw in Citrix NetScaler ADC and NetScaler Gateway that the vendor and NVD describe as allowing denial of service. NVD scores it CVSS 8.7 HIGH, CWE-119, and it is not listed in CISA KEV; EPSS is 0%. The item carries a CISA remediation due date of 2026-10-07, which is three days after this advisory, and the required action references BOD 26-04 and CISA Forensics Triage Requirements. The direct risk to EMEA financial services is availability loss on internet-facing NetScaler appliances, not code execution: the source text for this CVE names denial of service only. The wider context matters more than the single CVE. Three related NetScaler flaws in the same corpus are KEV-listed with due dates already passed (CVE-2026-8452, 2026-08-29; CVE-2026-88771, 2026-09-30; CVE-2026-19490, 2026-09-12), and CVE-2026-8452 is reported exploited in the wild. Treat CVE-2026-88779 as the newest entry in an active NetScaler patch cycle, not as an isolated bug. ## 2\. Regulatory framing | Article | Trigger (the fact in this item) | Practical impact | | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | DORA Art. 17 | A denial-of-service flaw in an internet-facing NetScaler appliance can interrupt the ICT services that depend on it, and the item sets a remediation due date of 2026-10-07. | The incident-management process must cover loss of the NetScaler path, including detection, triage and restoration steps for the appliances that terminate remote access and load balancing. | | DORA Art. 19 | If exploitation of CVE-2026-88779 or the KEV-listed NetScaler flaws causes an outage that meets the major-incident thresholds, reporting to the competent authority is engaged. | Reporting timelines and evidence capture must be ready before an outage, because the KEV entries in this cycle are already past their CISA due dates. | | NIS2 Art. 21(2)(d) | NetScaler is a supply-chain component, and the vendor fix plus the CISA BOD 26-04 required action are the supply-chain security measures in scope. | Supply-chain security measures must include tracking vendor advisories for NetScaler and applying the vendor builds within a defined window. | No other article in the regulatory reference is engaged by the facts here. DORA Art. 18, 24, 28, 29, 30 and NIS2 Art. 23 and UK NIS 2018 are not triggered by anything distinctive in this item. ## 3\. Technical analysis & attack chain The source material for CVE-2026-88779 is thin. NVD records it as CWE-119, improper restriction of operations within the bounds of a memory buffer, affecting Citrix NetScaler ADC (formerly Citrix ADC) and Citrix NetScaler Gateway (formerly Citrix Gateway), with denial of service as the stated outcome. No attack vector, port, protocol, authentication requirement, or affected version is given in the provided content. The verified reference data scores it CVSS 8.7 HIGH, not in CISA KEV, EPSS 0%. Do not read the 8.7 as evidence of remote code execution: the source text for this CVE says denial of service only. Confirmed steps, from the source facts: 1. The target is a Citrix NetScaler ADC or NetScaler Gateway appliance. Both product lines are named in the CVE record. 2. The flaw is a memory-buffer bounds violation (CWE-119) in the appliance. 3. Successful exploitation produces a denial of service against the appliance. That is the full confirmed chain. The source does not state how the buffer is reached, whether authentication is required, which interface or virtual server type is exposed, or which builds are affected. Those gaps are not filled here. The related corpus gives the surrounding picture, and it is the part a defender can act on. CVE-2026-8452 is a NetScaler ADC and Gateway memory-buffer flaw that Citrix disclosed on 30 June 2026 and described as a memory overflow leading to unpredictable or erroneous behavior and denial of service; CISA added it to KEV and gave federal agencies until 2026-08-29 to remediate, and Help Net Security reports it is being exploited in the wild. CVE-2026-88771 is an improper input validation flaw in the same products that could allow an unauthenticated attacker to execute arbitrary commands, KEV-listed with a 2026-09-30 due date. CVE-2026-19490 is an authentication bypass using an alternate path or channel, KEV-listed with a 2026-09-12 due date; per the CVE record, when the appliance is configured as an AAA virtual server or as a Gateway (SSL VPN, ICA Proxy, CVPN, or RDP Proxy), an unauthenticated remote actor may bypass authentication. CVE-2026-88772 is a further memory-buffer flaw in the same products that could allow remote code execution or denial of service, KEV-listed with a 2026-09-30 due date. The pattern across the cycle is that NetScaler appliances are being hit through the remote-access and AAA functions, with at least one flaw (CVE-2026-8452) confirmed exploited. CVE-2026-88779 sits in the same memory-buffer class as CVE-2026-8452 and CVE-2026-88772 but is scored for denial of service only, and it is not KEV-listed. Confidence caveats. The exploitation-in-the-wild claim for CVE-2026-8452 rests on a single source, Help Net Security, reporting CISA's KEV addition; the KEV entry itself is in the corpus but the exploitation detail is single-sourced. No actor, tooling, malware family, or campaign is named anywhere in the provided sources, so no attribution is offered. No indicators of compromise, file paths, registry keys, or command lines appear in the source material for any of these CVEs. The CISA due date of 2026-10-07 applies to CVE-2026-88779 per the item; the other due dates in this section belong to their own CVEs and are already past. ## 4\. Mitigation & containment P1 (within 24 hours) - Identify every NetScaler ADC and NetScaler Gateway appliance in the estate and record which are internet-facing. The CISA required action states stakeholders are responsible for evaluating each asset's internet exposure. - Apply the vendor mitigations for CVE-2026-88779 in line with the vendor instructions and the CISA BOD 26-04 guidance referenced in the item. The source does not name a fixed build, so take the build from the vendor security bulletin rather than from this advisory. - Confirm the KEV-listed NetScaler flaws in this cycle are already remediated: CVE-2026-8452 (due 2026-08-29), CVE-2026-19490 (due 2026-09-12), CVE-2026-88771 and CVE-2026-88772 (both due 2026-09-30). All four due dates have passed. If any appliance is still unpatched, treat it as overdue, not scheduled. - Where a mitigation is unavailable, the CISA required action states to follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product. For an internet-facing appliance that cannot be patched, removing it from direct internet exposure is the containment step. P2 (within 72 hours) - Restrict management and AAA interfaces on NetScaler appliances to known administrative networks. CVE-2026-19490 in this cycle is exploitable when the appliance runs as an AAA virtual server or as a Gateway (SSL VPN, ICA Proxy, CVPN, or RDP Proxy), so those configurations carry the highest exposure. - Capture forensic triage data per the CISA Forensics Triage Requirements referenced in the item, so that an availability event can be reconstructed after the fact. - Review authentication and session logs on the appliances for the period since the earliest KEV due date in this cycle (2026-08-29), looking for anomalous AAA or Gateway sessions. P3 (within 7 days) - Fold NetScaler into the supply-chain review required under NIS2 Art. 21(2)(d): a defined window for applying vendor builds, and a named owner for NetScaler advisories. - Rehearse the DORA Art. 17 incident-management path for loss of the NetScaler path, including who declares an outage and how DORA Art. 19 reporting thresholds are assessed. ## 5\. Indicators of compromise No indicators of compromise available in the source material. The provided sources contain no hashes, domains, IP addresses, file paths, registry keys, or command lines for CVE-2026-88779 or any of the related NetScaler CVEs. Nothing is fabricated to fill this section. Behavioural indicators | behaviour | where to observe | confidence | | ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------- | | Denial of service against a NetScaler ADC or Gateway appliance (CVE-2026-88779) | Appliance availability monitoring, load-balancer health checks, NetScaler system logs | High for the CVE description; no observed exploitation detail in source | | Exploitation of the memory-buffer flaw CVE-2026-8452 in the wild | Appliance logs and availability monitoring; KEV-listed, due date passed | Single-sourced (Help Net Security reporting CISA KEV); verify before enforcement | | Unauthenticated command execution via improper input validation (CVE-2026-88771) | NetScaler command and audit logs | High for the CVE description; KEV-listed | | Authentication bypass on an AAA virtual server or Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) configuration (CVE-2026-19490) | NetScaler AAA and Gateway session logs | High for the CVE description; KEV-listed | ## 6\. Detection Insufficient indicators to author detection rules. The sources give no distinctive strings, command-line flags, mutex names, scheduled-task or service names, file names or paths, registry keys, or hard-coded values for CVE-2026-88779 or the related NetScaler CVEs. A rule built from CVE identifiers or product names would detect reporting about the flaw, not the flaw, so none is emitted. ## CVE assessment 1 referenced CVE | CVE | CVSS | Exploited | EPSS | Summary | | -------------------------------------------------------------------------------- | -------- | --------- | ---- | ------------------------------------------------------------------------------------------------------------------------------- | | [CVE-2026-88779](https://nvd.nist.gov/vuln/detail/CVE-2026-88779?ref=f4n6.co.uk) | 8.7 High | — | 0% | Vulnerability in NetScaler ADC and NetScaler Gateway. This issue affects ADC: before 14.1-73.41, before 13.1-64.28, before 14.… | ## 7\. Sources - NVD, CVE-2026-88779 detail, https://nvd.nist.gov/vuln/detail/CVE-2026-88779, published 2026-10-03. - NVD, CVE-2026-88772 detail (CISA KEV), https://nvd.nist.gov/vuln/detail/CVE-2026-88772. - NVD, CVE-2026-8452 detail (CISA KEV), https://nvd.nist.gov/vuln/detail/CVE-2026-8452. - NVD, CVE-2026-88771 detail (CISA KEV), https://nvd.nist.gov/vuln/detail/CVE-2026-88771. - NVD, CVE-2026-19490 detail (CISA KEV), https://nvd.nist.gov/vuln/detail/CVE-2026-19490. - Help Net Security, Previously patched Citrix NetScaler flaw exploited in the wild (CVE-2026-8452), https://www.helpnetsecurity.com/2026/08/27/netscaler-adc-gateway-cve-2026-8452/, 2026-08-27. - Help Net Security, Citrix urges customers to fix critical NetScaler authentication bypass (CVE-2026-19490), https://www.helpnetsecurity.com/2026/08/21/citrix-netscaler-gateway-cve-2026-19490/, 2026-08-21. ## 8\. Adverse Trace position Adverse Trace assesses CVE-2026-88779 at its verified CVSS 8.7 HIGH, not in CISA KEV, EPSS 0%, with denial of service as the stated impact and no code-execution claim in the source. The single CVE is not the exposure; the exposure is a NetScaler estate with four KEV-listed flaws whose CISA due dates have already passed and one of which is reported exploited in the wild on a single source. We will track the vendor security bulletin for the fixed builds, since the source material does not name them, and we will re-issue this advisory if exploitation of CVE-2026-88779 is confirmed or if the KEV status changes. Clients should confirm the four overdue KEV items are closed before treating CVE-2026-88779 as the priority. --- [Read the original source →](https://nvd.nist.gov/vuln/detail/CVE-2026-88779?ref=f4n6.co.uk) *Published via PulseTrace — Adverse Trace threat intelligence.*