ADC: Out-of-bounds Read
CVE-2026-8451 is a high-severity out-of-bounds read vulnerability in ADC from 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 72.61, 63.18, 37.272 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 14.2% chance of exploitation within 30 days, which is in the top 3.35% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update ADC to 72.61 or 63.18 or 37.272, whichever matches your release line, or a later version.
- Update Gateway to 72.61 or 63.18, whichever matches your release line, or a later version.
- Update Netscaler Application Delivery Controller to 13.1-37.272 or 13.1-63.18 or 14.1-72.61, 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 |
|---|---|---|---|
| NetScaler | ADC | 14.1 up to, but not including, 72.61; 13.1 up to, but not including, 63.18; 14.1 FIPs up to, but not including, 72.61; 13.1 FIPS and NDcPP up to, but not including, 37.272 | 72.61, 63.18, 37.272 |
| NetScaler | Gateway | 14.1 up to, but not including, 72.61; 13.1 up to, but not including, 63.18 | 72.61, 63.18 |
| Citrix | Netscaler Application Delivery Controller | before 13.1-37.272; 13.1 up to, but not including, 13.1-63.18; 14.1 up to, but not including, 14.1-72.61; 14.1-66.68 | 13.1-37.272, 13.1-63.18, 14.1-72.61 |
| Citrix | Netscaler Gateway | 13.1 up to, but not including, 13.1-63.18; 14.1 up to, but not including, 14.1-72.61 | 13.1-63.18, 14.1-72.61 |
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
Insufficient input validation in NetScaler ADC and NetScaler Gateway leading to memory overread if NetScaler ADC or NetScaler Gateway is configured as a SAML IDP
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
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
- 9.5 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 8.1 High severity
- 8.1 High severity
- 8.1 High severity
- 8.1 High severity
- 7.4 High severity
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