How severe is CVE-2026-20124?

CVE-2026-20124 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-20124 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-20124?

CVE-2026-20124 primarily affects Cisco Ios Xe. In total, 277 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-20124?

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-2026-20124 published?

CVE-2026-20124 was published on 2026-08-05 and last updated on 2026-09-17.

CVE-2026-20124

CVE-2026-20124 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 7.7. 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-772.

Key facts

Severity: High (CVSS 3.x base score 7.7)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-772
Affected product: Cisco Ios Xe
Published: 2026-08-05
Last modified: 2026-09-17

Description

A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to improper error handling when parsing SNMP requests. This vulnerability affects all versions of SNMP — Versions 1, 2c, and 3. An attacker could exploit this vulnerability by sending a malformed SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly. The attacker must have the SNMPv1 or v2c read-only or read-write community string or valid SNMPv3 user credentials on the affected device.

Frequently asked questions

What is CVE-2026-20124?: A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to improper error handling when parsing SNMP requests. This vulnerability affects all versions of SNMP — Versions 1, 2c, and 3. An attacker could exploit this vulnerability by sending a malformed SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly. The attacker must have the SNMPv1 or v2c read-only or read-write community string or valid SNMPv3 user credentials on the affected device.
How severe is CVE-2026-20124?: CVE-2026-20124 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-20124 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-20124?: CVE-2026-20124 primarily affects Cisco Ios Xe. In total, 277 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-20124?: 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-2026-20124 published?: CVE-2026-20124 was published on 2026-08-05 and last updated on 2026-09-17.

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-snmp-dos-ZAqNm4MD

Affected products (277)

cpe:2.3:o:cisco:ios_xe:3.13.9s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.10s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.6bs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.7as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.7bs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.7s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.8s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.9s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.10as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.10bs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.16.10s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.3asp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.3bsp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.3sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.4sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.5sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.6sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.7sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.8asp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.18.9sp:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.4:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.4a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.5:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.5a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.5b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.6:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.7:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.7a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.8:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.9:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.6.10:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.1a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.1b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.3:*:*:*:*:*:*:*

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