CVE-2023-6549

Citrix NetScaler ADC and NetScaler Gateway: Buffer Overflow

As of , CVE-2023-6549 in Citrix NetScaler ADC and NetScaler Gateway is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 17 January 2024
US federal deadline
7 February 202421 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.58Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
No score that dayThe EPSS file of the day CISA listed it has no score for it.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
Vendor advice: support.citrix.comLinks below, from CISA's entry.

What CISA says to do

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

CISA's required action

What the flaw is

Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

CISA's 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

The CVE record's description, from Citrix

CVE published
17 January 2024
Assigned by
Citrix
CVSS
8.2 High (CVSS 3.1, from the CNA)
CWE-119
Improper Restriction of Operations within the Bounds of a Memory Buffer
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
partial

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

NetScaler ADC and NetScaler Gateway: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2023-4966Buffer OverflowCitrix NetScaler ADC and NetScaler GatewayPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2023-3519Code InjectionCitrix NetScaler ADC and NetScaler GatewayPatch this weekRansomware use; Metasploit module; EPSS 0.990.99
CVE-2023-6548Code InjectionCitrix NetScaler ADC and NetScaler GatewayPatch soon0.03
CVE-2026-8452Improper Restriction of Operations within the Bounds of a Memory BufferCitrix NetScaler ADC and NetScaler GatewayPatch soon0.01

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