CVE-2023-4966

Exploitation

Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2023-10-18. Federal remediation due 2023-11-08. Known ransomware campaign use: reported by CISA.

SSVC decision

• ExploitationactiveCISA reports credible evidence of active exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

99.99% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 99.9% of scored records. A rank, not a probability.

NVD base score

7.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

NVD analysis status

Analyzed. NVD last modified this record on 2026-07-31.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2023-10-10 13:12Z3 YR AGO

Last updated

2026-07-31 03:55Z3 MO AGO

Reserved

2023-09-14

Assigning CNA

Citrix

Record state

PUBLISHED

Severity

Critical (CVSS 9.4)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Weaknesses

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferClass

Data version

5.2

Document digest

7735090e7dc5d9c0df986ce4465cf9d40d1f086647ce71f5b0aaa865b1b4fada

• support.citrix.comhttps://support.citrix.com/article/CTX579459
• packetstormsecurity.comhttp://packetstormsecurity.com/files/175323/Citrix-Bleed-Session-Token-Leakage-Proof-Of-Concept.html
• www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-4966government-resource