CVE-2026-88771
Citrix NetScaler: Improper Input Validation
As of , CVE-2026-88771 in Citrix NetScaler is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch now.
- Exploited
- Yes: CISA listed it on 27 September 2026
- US federal deadline
- 30 September 20263 days after CISA listed it. US federal civilian agencies must fix it by then.
- Used in ransomware campaigns
- Not known to CISA
- Forensic triage
- Required by CISA under BOD 26-04Agencies must also look for signs that attackers already got in.
- EPSS score
- 0.01Higher than 64% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
- Public exploit
- None foundNeither Metasploit nor Exploit-DB lists one.
- Fix
- Vendor advice: community.citrix.com and support.citrix.comLinks below, from CISA's entry.
What CISA says to do
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.
CISA's required action
- community.citrix.comRunning the provided IOCs in the NetScaler console may help identify indicators of exploitation. Customers must conduct forensic triage as…
- support.citrix.com
- support.citrix.com
What the flaw is
Citrix NetScaler ADC and NetScaler Gateway contain an improper input validation vulnerability that could allow an unauthenticated attacker to execute arbitrary commands.
CISA's description
Improper input validation 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 an unauthenticated attacker to execute arbitrary commands.
The CVE record's description, from NetScaler
- CVE published
- 27 September 2026
- Assigned by
- NetScaler
- CVSS
- 9.5 Critical (CVSS 4.0, from the CNA)
- CWE-20
- Improper Input Validation
- CWE-119
- Improper Restriction of Operations within the Bounds of a Memory Buffer
- CISA SSVC, exploitation
- active
- CISA SSVC, automatable
- yes
- CISA SSVC, technical impact
- total
Timeline
- The CVE record was published.
- CISA added it to its list of exploited vulnerabilities.
- The US federal deadline to fix it.
NetScaler: other exploited entries
| Vulnerability | Product | Our group | Listed | Deadline | EPSS |
|---|---|---|---|---|---|
| CVE-2026-19490Authentication Bypass Using an Alternate Path or Channel | Citrix NetScaler | Patch nowForensic triage required by CISA | 0.23 | ||
| CVE-2026-88772Improper Restriction of Operations within the Bounds of a Memory Buffer | Citrix NetScaler | Patch nowForensic triage required by CISA; listed in the last 14 days | 0.01 | ||
| CVE-2026-88779Improper Restriction of Operations within the Bounds of a Memory Buffer | Citrix NetScaler | Patch nowForensic triage required by CISA; listed in the last 14 days | 0.01 | ||
| CVE-2026-3055Out-of-Bounds Read | Citrix NetScaler | Patch this weekMetasploit module | 0.04 | ||
| CVE-2025-7775Memory Overflow | Citrix NetScaler | Patch soon | 0.20 |
Read further
- CVE recordcve.org
- NVD entrynvd.nist.gov
- CISA's catalogcisa.gov
- EPSS for this CVEapi.first.org