Is CVE-2021-34727 actively exploited?

No active exploitation of CVE-2021-34727 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-34727 be exploited remotely?

Yes. CVE-2021-34727 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-34727?

CVE-2021-34727 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2021-34727

CRITICAL

CVE-2021-34727

CWE-120Published: September 23, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official Description

A vulnerability in the vDaemon process in Cisco IOS XE SD-WAN Software could allow an unauthenticated, remote attacker to cause a buffer overflow on an affected device. This vulnerability is due to insufficient bounds checking when an affected device processes traffic. An attacker could exploit this vulnerability by sending crafted traffic to the device. A successful exploit could allow the attacker to cause a buffer overflow and possibly execute arbitrary commands with root-level privileges, or cause the device to reload, which could result in a denial of service condition.

NVD Source

Technical Analysis

CVE-2021-34727 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected Vendors & Products

Cisco49 product(s)

ios xe sd-wan1000 integrated services router1100-4g\/6g integrated services router1100-4p integrated services router1100-8p integrated services router1100 integrated services router1101-4p integrated services router1101 integrated services router1109-2p integrated services router1109-4p integrated services router1109 integrated services router1111x-8p integrated services router+37

Source: NVD CPE · 49 total CPE entries