Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial
Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read
- Published
- Jan 17, 2024
- Updated
- Jun 17, 2026
- EPSS
- 57.6% · 99th percentile
- CWE
- CWE-119
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
77
This week
Don’t wait for the next maintenance window.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 30 / 30 · Listed
- EPSS
- 17 / 30 · 57.6%
CISA SSVC decision
- Exploitation
- active
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 7.5
- CNA · Citrix
- 8.2
- 0.7 point gap
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Actively exploited in the wild
CISA added this to its Known Exploited Vulnerabilities catalog on Jan 17, 2024. That signals real attacks, not theory.
Remediation deadline for government agencies: Feb 7, 2024.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| citrix | netscaler application delivery controller | cpe:2.3:a:citrix:netscaler_application_delivery_controller |
| citrix | netscaler gateway | cpe:2.3:a:citrix:netscaler_gateway |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- citrix netscaler gateway13.0 and later · before 13.0-92.21
- citrix netscaler gateway13.1 and later · before 13.1-51.15
- citrix netscaler gateway14.1 and later · before 14.1-12.35
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Citrix). Independent of NVD's CPE analysis and usually ahead of it.
Cloud Software Group NetScaler ADC
- 14.1 and later · before 12.35affected · patch
- 13.1 and later · before 51.15affected · patch
- 13.0 and later · before 92.21affected · patch
- 13.1-FIPS and later · before 37.176affected · patch
- 12.1-FIPS and later · before 55.302affected · patch
- 12.1-NDcPP and later · before 55.302affected · patch
Same product
citrix: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-3519Unauthenticated remote code executionKEV99Now
- CVE-2025-5777NetScaler ADC and NetScaler Gateway - Insufficient input validation leading to memory overreadKEV97Now
- CVE-2023-4966Unauthenticated sensitive information disclosureKEV90Now
- CVE-2025-7775Memory overflow vulnerability leading to Remote Code Execution and/or Denial of ServiceKEV72This week
- CVE-2026-19490NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2026-19490KEV69This week
- CVE-2025-6543Memory overflow vulnerability leading to unintended control flow and Denial of ServiceKEV69This week
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Cloud Software Group NetScaler ADC | 12.35 | Vendor (CNA) |
| Cloud Software Group NetScaler ADC | 37.176 | Vendor (CNA) |
| Cloud Software Group NetScaler ADC | 51.15 | Vendor (CNA) |
| Cloud Software Group NetScaler ADC | 55.302 | Vendor (CNA) |
| Cloud Software Group NetScaler ADC | 92.21 | Vendor (CNA) |
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Nuclei detection template ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Nuclei detection template | Nuclei template CVE-2023-6549 | — |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- CISA KEV-1 d
- Published
- TodaySep 29, 2026+986 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2023-496699 days apartUnauthenticated sensitive information disclosureKEV90Now
- CVE-2025-6543525 days apartMemory overflow vulnerability leading to unintended control flow and Denial of ServiceKEV69This week
- CVE-2024-8534300 days apartMemory safety vulnerability leading to memory corruption and Denial of Service33Monitor
- CVE-2023-496782 days apartDenial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AA30Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory BufferCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Buffer ManipulationCAPEC-123likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- support.citrix.com/article/CTX584986/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20236548-and-cve20236549
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-6549
Vendor advisories and official records. Exploit/PoC links are deliberately left out.