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Cisco ACI Multi-Site CloudSec Encryption Information Disclosure Vulnerability

highCVE-2023-20185
A vulnerability in the Cisco ACI Multi-Site CloudSec encryption feature of Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an unauthenticated, remote attacker to read or modify intersite encrypted traffic. This vulnerability is due to an issue with the implementation of the ciphers that are used by the CloudSec encryption feature on affected switches. An attacker with an on-path position between the ACI sites could exploit this vulnerability by intercepting intersite encrypted traffic and using cryptanalytic techniques to break the encryption. A successful exploit could allow the attacker to read or modify the traffic that is transmitted between the sites. Cisco has deprecated and removed the ACI Multi-Site CloudSec encryption feature that is affected by this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-cloudsec-enc-Vs5Wn2sX Security Impact Rating: High CVE: CVE-2023-20185

CSIRTS triage

What
A vulnerability could allow an unauthenticated attacker to read or modify intersite encrypted traffic.
Who is affected
Users of Cisco Nexus 9000 Series Fabric Switches in ACI mode.
Urgency
High urgency due to the potential for significant data exposure.
Action
Since the affected feature has been deprecated, ensure that it is no longer in use.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
Cisco Security Advisories (INTL · vendor-psirt · site)
Severity
high
Published
2026-04-24
Exploitation
Not in CISA KEV at last sync

Original advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-aci-cloudsec-enc-Vs5Wn2sX?vs_f=Cisco%20Security%20Advisory%26vs_cat=Security%20Intelligence%26vs_type=RSS%26vs_p=Cisco%20ACI%20Multi-Site%20CloudSec%20Encryption%20Information%20Disclosure%20Vulnerability%26vs_k=1

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2023-20185coverage & exploitation statusNVD · CVE.org

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