CVE-2026-88778 TCP Initial Sequence Number (ISN) prediction
Attackers can predict TCP Initial Sequence Numbers to bypass security controls in Citrix NetScaler ADC and Gateway.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-88778?
CVE-2026-88778 is a high-severity vulnerability in Citrix NetScaler ADC, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Predictable exact value from previous values 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.
Weakness: CWE-342
Which versions are affected by CVE-2026-88778?
It affects 2 products.
Products include Citrix NetScaler ADC, Citrix Netscaler Gateway.
How do I fix CVE-2026-88778?
No fix has been published for CVE-2026-88778 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-88778 being exploited?
There is no known exploitation of CVE-2026-88778 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Citrix NetScaler ADC
- CVE-2023-3519 Citrix NetScaler ADC and NetScaler Gateway Code Injection
- CVE-2026-88771 Citrix NetScaler Improper Input Validation
- CVE-2026-88772 Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer
- CVE-2023-4966 Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow
- CVE-2026-19490 Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel
Sources
Also known as GHSA-mh3h-4j34-54mr.