CVE-2021-1378

Cisco StarOS Denial of Service Vulnerability

HIGH
7.5
CVSS Score
Published: February 17, 2021 at 04:55 PM UTC
Updated: June 17, 2026 at 03:31 AM UTC
1 product affected across 1 vendorStaros

Using Cisco ASR 5000 Series Software by Cisco?

Get instant alerts when new vulnerabilities affect Cisco ASR 5000 Series Software - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
HIGH7.5
Exploit prediction
EPSS 2%
SSVC
No known exploit

Description

A vulnerability in the SSH service of the Cisco StarOS operating system could allow an unauthenticated, remote attacker to cause an affected device to stop processing traffic, resulting in a denial of service (DoS) condition. The vulnerability is due to a logic error that may occur under specific traffic conditions. An attacker could exploit this vulnerability by sending a series of crafted packets to an affected device. A successful exploit could allow the attacker to prevent the targeted service from receiving any traffic, which would lead to a DoS condition on the affected device.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

21.9.0 ≤ v ≤ 21.19.10

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-400

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card