CVE-2019-1740: Cisco IOS and IOS XE Software Network-Based Application Recognition Denial of Service Vulnerabilities

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-03-28 · updated 2026-06-17
Weakness: CWE-20

Description

A vulnerability in the Network-Based Application Recognition (NBAR) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. This vulnerability are due to a parsing issue on DNS packets. An attacker could exploit this vulnerability by sending crafted DNS packets through routers that are running an affected version and have NBAR enabled. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition.

Affected products

Cisco IOS: 15.3(3)jd, 15.3(3)jd2, 15.3(3)jd3, 15.3(3)jd4, 15.3(3)jd5, 15.3(3)jd6 (+85)
Cisco IOS XE: 3.2.0ja, 3.16.0as, 3.16.0bs, 3.16.0cs, 3.16.0s, 3.16.1as (+52)

References

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