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CVE-2023-6549 Citrix CVE debrief

CVE-2023-6549 is a Citrix NetScaler ADC and NetScaler Gateway buffer overflow vulnerability that CISA added to its Known Exploited Vulnerabilities (KEV) catalog on 2024-01-17. For defenders, the key signal is not just the weakness class but the KEV status: CISA set a remediation due date of 2024-02-07 and instructed organizations to apply vendor mitigations or discontinue use if mitigations are unavailable.

Vendor
Citrix
Product
NetScaler ADC and NetScaler Gateway
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2024-01-17
Original CVE updated
2024-01-17
Advisory published
2024-01-17
Advisory updated
2024-01-17

Who should care

Organizations that operate Citrix NetScaler ADC or NetScaler Gateway appliances, especially internet-facing deployments; security teams responsible for patching, mitigation tracking, and exposure management; and incident response teams monitoring KEV-listed issues.

Technical summary

The public record identifies the issue as a buffer overflow in Citrix NetScaler ADC and NetScaler Gateway. CISA’s KEV entry marks it as a known exploited vulnerability and points defenders to Citrix’s security bulletin for mitigation guidance.

Defensive priority

High. KEV inclusion means CISA considers this vulnerability actively exploited in the wild, so exposed Citrix NetScaler deployments should be prioritized immediately against vendor guidance and remediation timelines.

Recommended defensive actions

  • Review Citrix’s security bulletin referenced by CISA for CVE-2023-6549 and follow the vendor’s mitigation instructions.
  • If mitigations are unavailable or cannot be deployed quickly, discontinue use of the affected product as CISA advises.
  • Inventory all Citrix NetScaler ADC and NetScaler Gateway instances, especially those reachable from the internet.
  • Confirm whether your environment was still running affected versions during the KEV remediation window.
  • Track remediation status against the CISA KEV due date and verify that compensating controls remain in place until full remediation is complete.

Evidence notes

This debrief is based on the supplied CVE record, CISA KEV source item, and official resource links. Supported facts include: the vulnerability name/class (buffer overflow), the affected product family (Citrix NetScaler ADC and NetScaler Gateway), KEV listing date (2024-01-17), and the due date (2024-02-07). The source item notes cite Citrix support article CTX584986 and the NVD record as official references. No CVSS score or exploit detail was supplied in the corpus.

Official resources

Publicly disclosed on 2024-01-17 via the CVE record and CISA KEV listing.