CVE-2022-20837

highpriority · track · 34EPSS 0.010 · 64 %ileEURUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
1.03% (64th) EPSS
CVSS 8.6 · high
Is it mine?
67 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-27

A vulnerability in the DNS application layer gateway (ALG) functionality that is used by Network Address Translation (NAT) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. This vulnerability is due to a logic error that occurs when an affected device inspects certain TCP DNS packets. An attacker could exploit this vulnerability by sending crafted DNS packets through the affected device that is performing NAT for DNS packets. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition on the affected device. Note: This vulnerability can be exploited only by sending IPv4 TCP packets through an affected device. This vulnerability cannot be exploited by sending IPv6 traffic.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

02

cvss

Technical severity, 0–10. One row per scoring source.

8.6
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 4
v3.18.6highAV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU
v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · ENISA EU
v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · psirt@cisco.com USexploitability 3.9 · impact 4
v3.17.9highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)
v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsecondary · Cisco PSIRT US
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-754USprimaryCWE-754US
05

affected products (67)

Products and version ranges known to be affected.

showing 20 of 67
06

advisories (1)

Vendor and ecosystem advisories describing this.

  • cisco-sa-alg-dos-KU9Z8kFXCisco IOS XE Software DNS NAT Protocol Application Layer Gateway Denial of Service Vulnerability2022-09-28csaf · cisco_csafUS

    A vulnerability in the DNS application layer gateway (ALG) functionality that is used by Network Address Translation (NAT) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. This vulnerability is due to a logic error that occurs when an affected device inspects certain TCP DNS packets. An attacker could exploit this vulnerability by sending crafted DNS packets through the affected device that is performing NAT for DNS packets. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition on the affected device. Note: This vulnerability can be exploited only by sending IPv4 TCP packets through an affected device. This vulnerability cannot be exploited by sending IPv6 traffic. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of the September 2022 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2022 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication. ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74745"]

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisco_csafNVDCVE.orgMITRE
published 2022-10-10modified 2026-06-17
10

references (5)

External citations — patches, advisories, analysis.

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