ADC: Predictable Exact Value from Previous Values
CVE-2026-88778 is a high-severity predictable exact value from previous values vulnerability in ADC from Citrix NetScaler, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 14.1-73.37, 13.1-64.23, 14.1-73.37 FIPS as the first without the flaw, so updating ADC to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.69% chance of exploitation within 30 days, higher than 53% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update ADC to 14.1-73.37 or 13.1-64.23 or 14.1-73.37 FIPS or 13.1.37.279 FIPS and NDcPP, whichever matches your release line, or a later version.
- Update Gateway to 14.1-73.37 or 13.1-64.23, whichever matches your release line, or a later version.
- Update Netscaler Application Delivery Controller to 13.1-64.23 or 13.1.37.279 or 14.1-73.37, whichever matches your release line, or a later version.
- Read the advisory on support.citrix.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Citrix NetScaler | ADC | before 14.1-73.37; before 13.1-64.23; before 14.1-73.37 FIPS; before 13.1.37.279 FIPS and NDcPP | 14.1-73.37, 13.1-64.23, 14.1-73.37 FIPS, 13.1.37.279 FIPS and NDcPP |
| Citrix NetScaler | Gateway | before 14.1-73.37; before 13.1-64.23 | 14.1-73.37, 13.1-64.23 |
| Citrix | Netscaler Application Delivery Controller | 13.1 up to, but not including, 13.1-64.23; 13.1 up to, but not including, 13.1.37.279; 14.1 up to, but not including, 14.1-73.37; 14.1-66.68 through 14.1-73.37 | 13.1-64.23, 13.1.37.279, 14.1-73.37 |
| Citrix | Netscaler Gateway | 13.1 up to, but not including, 13.1-64.23; 14.1 up to, but not including, 14.1-73.37 | 13.1-64.23, 14.1-73.37 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.8 | High | CNA |
| CVSS 3.1 | 7.5 | High | NVD |
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Predictable Exact Value from Previous Values
An exact value or random number can be precisely predicted by observing previous values.
How developers prevent this class of flaw
- Increase the entropy used to seed a PRNG.
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems. Consult FIPS 140-2 Annex C (Approved Random Number Generators).
- Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.
More Predictable Exact Value from Previous Values vulnerabilities (CWE-342)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in ADC
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.2 High severity
- 10.0 Critical severity
- 8.1 High severity
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