Our automated tracking framework flagged that CISA added CVE-2026-88772 (Citrix NetScaler) to the Known Exploited Vulnerabilities (KEV) catalog on October 4, 2026. A KEV listing is CISA’s official confirmation that the flaw is being exploited in the wild — U.S. federal agencies must patch it by a fixed deadline. Here is what our data shows.
What CISA Reported
CISA describes the flaw as follows: “Citrix NetScaler ADC and NetScaler Gateway contain an improper restriction of operations within the bounds of a memory buffer vulnerability that could allow for remote code execution or denial of service”
Under Binding Operational Directive rules, U.S. federal agencies must remediate CVE-2026-88772 by September 30, 2026 — a 3-day window. Private organizations are not bound by the deadline, but CISA treats it as the benchmark for how urgently a confirmed-exploited flaw should be patched.
The Details
| CVE | CVE-2026-88772 |
| Vendor / product | Citrix NetScaler |
| Vulnerability | Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability |
| CVSS base score | 8.1 |
| Added to KEV | September 27, 2026 |
| Days public before listing (NVD → KEV lag) | 0 |
| Federal patch deadline | September 30, 2026 |
| Known ransomware use | No |
How This Compares to Citrix’s Track Record
This one was listed on or before its public disclosure (a lag of 0 days) — a zero-day exploited at or before the vulnerability was even published.
| Citrix in the CISA KEV catalog | Value |
|---|---|
| Tracked KEV entries | 26 |
| Median lag (public → KEV listing) | 47 days |
| 0-day rate (exploited at or before disclosure) | 27% |
| Entries tied to known ransomware campaigns | 7 |
For perspective, the median across all 1733 tracked KEV entries is 245 days — Citrix’s exploited vulnerabilities are flagged faster than the catalog average.
Other Recent Citrix KEV Additions
The most recent Citrix vulnerabilities CISA has confirmed as actively exploited, from our tracker:
| CVE | Product | Added to KEV | Lag (days) | Ransomware |
|---|---|---|---|---|
| CVE-2026-88771 | NetScaler | September 27, 2026 | 0 | No |
| CVE-2026-19490 | NetScaler | September 9, 2026 | 21 | No |
| CVE-2026-8452 | NetScaler ADC and NetScaler Gateway | August 26, 2026 | 57 | No |
| CVE-2026-3055 | NetScaler | March 30, 2026 | 7 | No |
| CVE-2025-7775 | NetScaler | August 26, 2025 | 0 | No |
Defense guide: How to Detect DDoS Attack: Warning Signs & Defense Playbook — detection signals, attack chain and response steps for this class of attack.
What This Means for Defenders
CISA has added CVE-2026-88772 to its Known Exploited Vulnerabilities (KEV) catalog, flagging a vulnerability in Citrix NetScaler. With a CVSS base score of 8.1, this vulnerability poses a significant risk. It was added to the KEV catalog on 2026-09-27, the same day it became public. This 0-day lag between public availability and KEV listing, coupled with a federal patch deadline of 2026-09-30, means organizations using Citrix NetScaler need to patch immediately.
The 0-day lag suggests attackers were leveraging this vulnerability at or near the time of public disclosure. Organizations with internet-facing Citrix NetScaler deployments are most exposed. Patching before the September 30th deadline is critical. There’s no known ransomware use associated with this CVE.
If you cannot apply the patch by the September 30th deadline, restrict access to affected systems. Isolate them, apply strict network segmentation, and monitor for unusual activity originating from or targeting NetScaler appliances. These measures reduce immediate risk but aren’t a substitute for prompt patching, which is the primary defense against active exploitation of CVE-2026-88772.
Related Coverage
- Citrix’s CVE-2026-8452 Was Exploited in 57 Days — Faster Than Its 183-Day Median (August 2026)
- Citrix’s CVE-2026-19490 Was Exploited in 21 Days — Faster Than Its 120-Day Median (September 2026)
How We Track This
This report was generated from our CISA KEV Lag Tracker, which syncs the official CISA KEV catalog daily and records the date each CVE is added. For every entry we retrieve the original NVD publication date and compute the lag in calendar days. No dates or figures on this page are estimated or taken from third-party sources — they come directly from CISA and NVD records.
