Multiple Vendor HMAC Authentication SNMPv3 Authentication Bypass

critical Nessus Plugin ID 40449


The SNMP server running on this host is affected by an authentication bypass vulnerability.


SNMPv3 HMAC verification relies on the client to specify the HMAC length. This makes it possible for remote attackers to bypass SNMP authentication via repeated attempts with a HMAC length value of 1, which causes only the first byte of the authentication hash to be checked.

This issue affects SNMP implementations from multiple vendors.


This vulnerability affects multiple products from multiple vendors. Check with your vendor for the appropriate solution.

See Also

Plugin Details

Severity: Critical

ID: 40449

File Name: snmpv3_authentication_bypass.nasl

Version: 1.25

Type: remote

Family: SNMP

Published: 7/31/2009

Updated: 2/28/2022

Risk Information


Risk Factor: High

Score: 7.4


Risk Factor: Critical

Base Score: 10

Temporal Score: 8.3

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2008-0960


Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9.1

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:F/RL:O/RC:C

Vulnerability Information

Required KB Items: SNMP/v3/username, SNMP/v3/Supported

Exploit Available: true

Exploit Ease: Exploits are available

Exploited by Nessus: true

Patch Publication Date: 6/9/2008

Vulnerability Publication Date: 5/31/2008

Exploitable With

CANVAS (D2ExploitPack)

Reference Information

CVE: CVE-2008-0960

BID: 29623

CWE: 287

CERT: 878044