CVE-2021-1446
No exploitation reported by the sources we read.
- Published2021-03-24
- WeaknessCWE-754
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
A vulnerability in the DNS application layer gateway (ALG) functionality used by Network Address Translation (NAT) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to a logic error that occurs when an affected device inspects certain DNS packets. An attacker could exploit this vulnerability by sending crafted DNS packets through an affected device that is performing NAT for DNS packets. A successful exploit could allow an attacker to cause the device to reload, resulting in a denial of service (DoS) condition on an affected device. The vulnerability can be exploited only by traffic that is sent through an affected device via IPv4 packets. The vulnerability cannot be exploited via IPv6 traffic.
Timeline
dates in UTC- 2021-03-2420:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-1446?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-1446?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 3.7 | = 3.7.0bs | no fix published | NVD |
| 3.7 | = 3.7.0s | no fix published | NVD |
| 3.7 | = 3.7.0xas | no fix published | NVD |
| 3.7 | = 3.7.0xbs | no fix published | NVD |
| 3.7 | = 3.7.1as | no fix published | NVD |
| 3.7 | = 3.7.1s | no fix published | NVD |
| 3.7 | = 3.7.2s | no fix published | NVD |
| 3.7 | = 3.7.2ts | no fix published | NVD |
| 3.7 | = 3.7.3s | no fix published | NVD |
| 3.7 | = 3.7.4as | no fix published | NVD |
| 3.7 | = 3.7.4s | no fix published | NVD |
| 3.7 | = 3.7.5s | no fix published | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
Advisories and patches
- tools.cisco.comVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2021-03-24
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-1446?
Is CVE-2021-1446 actively exploited?
What is the CVSS score for CVE-2021-1446?
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