Vulnerability · Published Sep 23, 2021 · Assigned by cisco

CVE-2021-1616Cisco IOS XE Software H.323 Application Level Gateway Bypass Vulnerability

Medium 4.7

In plain English

A medium-severity security flaw in Cisco IOS XE Software from Cisco. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 68% of all known vulnerabilities).

Severity (CVSS 3.1)4.7Medium

Exploit odds (30 days)1.2%top 31.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
Cisco	Cisco IOS XE Software	n/a

Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

References

20210922 Cisco IOS XE Software H.323 Application Level Gateway Bypass Vulnerability vendor-advisory, x_refsource_CISCO