CVE-2026-20124
HighCVSS 7.7Exploitation Probability (EPSS)
Low risk27th percentile - higher than 27% of all known CVEs
Summary
A vulnerability in the SNMP subsystem of Cisco IOS XE Software allows an authenticated remote attacker to cause a device reload, resulting in a denial of service (DoS). The issue is due to improper error handling when parsing SNMP requests and affects all SNMP versions (1, 2c, 3).
Risk Assessment
The attack can cause an unexpected device reload, leading to network disruptions and service unavailability. SNMP credentials are required.
Recommendation
Apply Cisco IOS XE updates that address this vulnerability, and restrict SNMP access to trusted hosts and users only.
Other vulnerabilities in Cisco IOS XE Software
See all- CVE-2026-20272Critical
As part of an internal security review in Cisco IOS XE Software, multiple vulnerabilities related to improper neutralization of special elements (CWE-74) were discovered. Hardened software releases addressing these issues have been issued.
- CVE-2026-20267Critical
As part of an internal security review in Cisco IOS XE Software, multiple vulnerabilities related to improper access control (CWE-284) were discovered. Hardened software releases addressing these issues have been issued.
- CVE-2017-12229Critical
A vulnerability in the web-based user interface (web UI) of Cisco IOS XE 3.1 through 16.5 allows an unauthenticated remote attacker to bypass authentication to the REST API. The issue is due to insufficient input validation for the REST API.
- CVE-2026-20311Medium
A vulnerability in the web-based management interface of Cisco IOS XE Software could allow an authenticated, remote attacker with low privileges to cause a denial of service (DoS) condition on an affected device. This is due to insufficient error handling in the web-based management interface. An attacker could exploit this by authenticating with a malformed certificate, potentially causing the device to reload.
- CVE-2026-20308Medium
A vulnerability in the web-based management interface of Cisco IOS XE Software allows an authenticated remote attacker with low privileges to perform a DoS attack. The issue is due to insufficient input validation, and exploitation can make the interface unresponsive.
- CVE-2026-20273High
A vulnerability in Cisco IOS XE Software related to improper input validation (CWE-20), discovered during an internal security review. It is addressed in a software hardening release.
- CVE-2026-20271High
A vulnerability in Cisco IOS XE Software related to insufficient control flow management (CWE-691), discovered during an internal security review. It is addressed in software hardening releases.
- CVE-2026-20270High
A vulnerability in Cisco IOS XE Software related to incorrect calculation issues (CWE-682), discovered during an internal security review. It is addressed in software hardening releases.
- CVE-2026-20269High
A vulnerability in Cisco IOS XE Software related to improper control of a resource through its lifetime (CWE-664), discovered during an internal security review. It is addressed in software hardening releases.
- CVE-2026-20268High
A vulnerability in Cisco IOS XE Software related to improper restriction of operations within the bounds of a memory buffer (CWE-119), discovered during an internal security review. It is addressed in software hardening releases.
Original NVD description (English source)
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.