How severe is CVE-2019-1740?

CVE-2019-1740 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2019-1740 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-1740?

CVE-2019-1740 primarily affects Cisco Ios Xe. In total, 149 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-1740?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-1740 published?

CVE-2019-1740 was published on 2019-03-28 and last updated on 2026-06-17.

CVE-2019-1740

CVE-2019-1740 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 7.8
EPSS exploit prediction: 2% (80th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Ios Xe
Published: 2019-03-28
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2019-1740?: 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.
How severe is CVE-2019-1740?: CVE-2019-1740 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2019-1740 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-1740?: CVE-2019-1740 primarily affects Cisco Ios Xe. In total, 149 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-1740?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-1740 published?: CVE-2019-1740 was published on 2019-03-28 and last updated on 2026-06-17.

References

Affected products (149)

cpe:2.3:o:cisco:ios_xe:3.2.0ja:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.0as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.0bs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.0cs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.1as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.2as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.2bs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.3as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4bs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4cs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4ds:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4es:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4gs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.5as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.5s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.17.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.17.1as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.17.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.17.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.17.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.17.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.0as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.0sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1asp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1bsp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1csp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1gsp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1hsp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1isp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.1sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.2asp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.2s:*:*:*:*:*:*:*

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