Vulnerability Name:

CVE-2021-1616 (CCN-209869)

Assigned:2020-11-13
Published:2021-09-22
Updated:2022-10-24
Summary:A vulnerability in the H.323 application level gateway (ALG) used by the Network Address Translation (NAT) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass the ALG. This vulnerability is due to insufficient data validation of traffic that is traversing the ALG. An attacker could exploit this vulnerability by sending crafted traffic to a targeted device. A successful exploit could allow the attacker to bypass the ALG and open connections that should not be allowed to a remote device located behind the ALG.
Note: This vulnerability has been publicly discussed as NAT Slipstreaming.
CVSS v3 Severity:4.7 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N)
4.1 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): None
Integrity (I): Low
Availibility (A): None
4.7 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N)
4.1 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): None
Integrity (I): Low
Availibility (A): None
CVSS v2 Severity:4.3 Medium (CVSS v2 Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Medium
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): Partial
Availibility (A): None
4.0 Medium (CCN CVSS v2 Vector: AV:N/AC:L/Au:S/C:N/I:P/A:N)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Athentication (Au): Single_Instance
Impact Metrics:Confidentiality (C): None
Integrity (I): Partial
Availibility (A): None
Vulnerability Type:CWE-Other
Vulnerability Consequences:Bypass Security
References:Source: MITRE
Type: CNA
CVE-2021-1616

Source: XF
Type: UNKNOWN
cisco-cve20211616-sec-bypass(209869)

Source: CCN
Type: Cisco Security Advisory cisco-sa-iosxe-h323alg-bypass-4vy2MP2Q
Cisco IOS XE Software H.323 Application Level Gateway Bypass Vulnerability

Source: CISCO
Type: Vendor Advisory
20210922 Cisco IOS XE Software H.323 Application Level Gateway Bypass Vulnerability

Vulnerable Configuration:Configuration 1:
  • cpe:/o:cisco:ios_xe:*:*:*:*:*:*:*:* (Version < 17.6.1)

    • Configuration CCN 1:
  • cpe:/o:cisco:ios_xe_software:*:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    cisco ios xe *
    cisco ios xe software *