CVE-2021-1616
low-risk
Published 2021-09-23
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.
Do I need to act?
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0.43% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.7/10
Medium
NETWORK
/ LOW complexity
Affected Products (1)
Affected Vendors
References (2)
26
/ 100
low-risk
Severity
19/34 · Moderate
Exploitability
2/34 · Minimal
Exposure
5/34 · Minimal