What is CVE-2021-1616?

CVE-2021-1616 is a medium-severity vulnerability in Cisco iOS Xe Software, classified under Protection Mechanism Failure. CVSS score: 4.7/10. Published 2021-09-23.

How severe is CVE-2021-1616?

Medium severity. CVSS v3 base score is 4.7 out of 10.

Is CVE-2021-1616 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Cisco iOS Xe Software

CVE-2021-1616

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.

EPSS: 0.012 (64.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N.

Affected products

Cisco Ios Xe Software — versions n/a
Cisco Ios_xe

Weakness classification (CWE)

CWE-693 — Protection Mechanism Failure

Public proof-of-concept exploits

References

psirt@cisco.com (x_refsource_CISCO, vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2021-1616?: CVE-2021-1616 is a medium-severity vulnerability in Cisco iOS Xe Software, classified under Protection Mechanism Failure. CVSS score: 4.7/10. Published 2021-09-23.
How severe is CVE-2021-1616?: Medium severity. CVSS v3 base score is 4.7 out of 10.
Is CVE-2021-1616 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.