TI-2022-05396 Aliases CVE-2022-20837 GHSA-7cwr-j6cv-fjjp

Cisco IOS XE Software DNS NAT Protocol Application Layer Gateway Denial of Service Vulnerability

MEDIUM 45CWE-754Published 2022-10-10 · Updated 2024-11-01

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · None · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.0103 63rd percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Cisco	Cisco IOS XE Software	all versions	—	No fix listed	CNA

Cisco IOS XE Software VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 5

CPE	Versions	Role	Vendor
cpe:2.3:o:cisco:ios_xe:-:::::::*	not specified by NVD	Vulnerable	Cisco
cpe:2.3:h:cisco:asr_1000-esp100-x:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:asr_1000-esp200-x:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:catalyst_8500:-:::::::*	not specified by NVD	Running on	Cisco
cpe:2.3:h:cisco:catalyst_8500-4qc:-:::::::*	not specified by NVD	Running on	Cisco

cpe:2.3:o:cisco:ios_xe:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Cisco
cpe:2.3:h:cisco:asr_1000-esp100-x:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:asr_1000-esp200-x:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:catalyst_8500:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
cpe:2.3:h:cisco:catalyst_8500-4qc:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2022-20837
2026-10-03 Alias added: GHSA-7cwr-j6cv-fjjp

References

Advisory 1

20220928 Cisco IOS XE Software DNS NAT Protocol Application Layer Gateway Denial of Service Vulnerability

TI-2023-06904 Cisco is providing an update for the ongoing investigation into observed exploitation of… KEVCVSS 3.1CRITICAL 10.0
TI-2018-00122 Memory corruption in Cisco IOS and IOS XE KEVCVSS 3.1CRITICAL 9.8
TI-2017-02977 Improper input validation in Cisco IOS and IOS XE Software KEVCVSS 3.1CRITICAL 9.8
TI-2018-00135 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.8
TI-2017-04498 Memory corruption in Cisco IOS KEVCVSS 3.1HIGH 8.8
TI-2017-04497 Memory corruption in Cisco IOS XE Software KEVCVSS 3.1HIGH 8.8

See all 561 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences