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Exploited vulnerability · CISA KEV

Is CVE-2026-88779 exploited? Yes: in CISA KEV since 4 Oct 2026

Gociux · Citrix NetScaler · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-88779, Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 4 Oct 2026, the day it was published. It affects Citrix NetScaler, an internet-facing product of the kind attackers use for initial access. If you run it, CISA's required action is: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

exploitedYesCISA KEV · 4 Oct 2026
ransomwareNot knownno confirmed use
EPSStop 5%very likely to be exploited
severity8.7CVSS 4.0 · high
US federal due7 Oct 2026BOD 22-01 deadline

What it is

Citrix NetScaler ADC (formerly Citrix ADC) and Citrix NetScaler Gateway (formerly Citrix Gateway) contain an improper restriction of operations within the bounds of a memory buffer vulnerability that could allow for a denial of service.

VendorCitrix (27 exploited CVEs in KEV)
ProductNetScaler
VulnerabilityCitrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
WeaknessCWE-119
Published4 Oct 2026
Added to KEV4 Oct 2026
Reported by (CNA)NetScaler

What to do

  1. Check whether you run it. Look for NetScaler in your asset inventory, including appliances and cloud images. Stack check lists every exploited Citrix CVE at once.
  2. Apply the fix. Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 4 Oct 2026.
  4. Get told next time. Email alerts when CISA adds a CVE for Citrix.

Other exploited CVEs in NetScaler

References

Questions

Is CVE-2026-88779 being exploited?

Yes. CISA added CVE-2026-88779 to the Known Exploited Vulnerabilities catalog on 4 Oct 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2026-88779 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2026-88779?

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. Check Citrix's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected NetScaler and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in October 2026 · Citrix scorecard · act-now radar.

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