What is CVE-2015-6421?

CVE-2015-6421 is a high-severity vulnerability in Cisco Wide Area Application Services, classified under CWE-399. CVSS score: 7.5/10. Published 2016-01-27.

How severe is CVE-2015-6421?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Cisco Wide Area Application Services

CVE-2015-6421

cifs-ao in the CIFS optimization functionality on Cisco Wide Area Application Service (WAAS) and Virtual WAAS (vWAAS) devices 5.x before 5.3.5d and 5.4 and 5.5 before 5.5.3 allows remote attackers to cause a denial of service (resource consumption and device reload) via crafted network traffic, aka Bug ID CSCus85330.

Published 2016-01-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.019 (79.2th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.019 · newest: 0.019 · change: 0.000

Affected products

Cisco Wide Area Application Services — versions 5.1.1, 5.1.1a, 5.1.1b

Weakness classification (CWE)

CWE-399

References

www.securitytracker.com/id/1034831 (vdb-entry)
tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160127… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2015-6421?: CVE-2015-6421 is a high-severity vulnerability in Cisco Wide Area Application Services, classified under CWE-399. CVSS score: 7.5/10. Published 2016-01-27.
How severe is CVE-2015-6421?: High severity. CVSS v3 base score is 7.5 out of 10.