CVE-2022-20685
HighCVSS 7.5Exploitation Probability (EPSS)
Elevated risk70th percentile - higher than 70% of all known CVEs
Summary
A vulnerability in the Modbus preprocessor of the Snort detection engine could allow an unauthenticated, remote attacker to cause a denial of service (DoS). The issue is due to an integer overflow while processing Modbus traffic. Exploitation involves sending crafted Modbus traffic.
Risk Assessment
Exploitation could cause the Snort process to hang, stopping traffic inspection and potentially exposing the network to threats.
Recommendation
Update to patched Cisco software and monitor Modbus traffic for malicious patterns.
Other vulnerabilities in Snort
See all- CVE-2016-1417High
The vulnerability in Snort 2.9.7.0-WIN32 related to an untrusted search path allows remote attackers to execute arbitrary code and conduct DLL hijacking attacks via a malicious tcapi.dll file located in the same folder as a processed pcap file.
- CVE-2026-20068Medium
Vulnerability in the Snort 3 detection engine in multiple Cisco products allows an unauthenticated, remote attacker to cause the engine to restart, interrupting packet inspection. It is due to incomplete error checking when parsing RPC data.
- CVE-2026-20067Medium
Multiple Cisco products are affected by a vulnerability in the Snort 3 detection engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to incomplete error checking when parsing the Multicast DNS fields of the HTTP header. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine unexpectedly restarts.
- CVE-2026-20066Medium
Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in the JSTokenizer normalization logic when the HTTP inspection normalizes JavaScript. An attacker could exploit this vulnerability by sending crafted HTTP packets through an established connection that is parsed by Snort 3. A successful exploit could allow the attacker to cause a DoS condition when the Snort 3 Detection Engine restarts unexpectedly. JSTokenizer is not enabled by default.
- CVE-2026-20058Medium
Multiple Cisco products are affected by vulnerabilities in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash. These vulnerabilities are due to improper error checking when decompressing VBA data. An attacker could exploit these vulnerabilities by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to unexpectedly restart, causing a DoS condition.
- CVE-2023-20267Medium
A vulnerability in the IP geolocation rules of Snort 3 could allow an unauthenticated, remote attacker to bypass IP address restrictions. This is due to improper parsing of the configuration for IP geolocation rules.
- CVE-2023-20246Medium
Multiple Cisco products are affected by a vulnerability in Snort access control policies that could allow an unauthenticated, remote attacker to bypass configured policies. This is due to a logic error when access control policies are populated. An attacker could exploit this by establishing a connection, potentially bypassing access control rules.
- CVE-2021-40116High
A vulnerability in Snort rules in multiple Cisco products could allow an unauthenticated, remote attacker to cause a denial of service (DoS). The issue is due to improper handling of Block with Reset or Interactive Block with Reset actions if a rule is configured without proper constraints. Exploitation involves sending a crafted IP packet.
- CVE-2021-40114Medium
A vulnerability in the Snort detection engine of multiple Cisco products when processing ICMP traffic could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The issue is due to improper memory resource management while processing ICMP packets. An attacker could send a series of ICMP packets through an affected device, potentially exhausting resources and causing a reload.
- CVE-2021-1236Medium
A vulnerability in the Snort application detection engine of multiple Cisco products could allow an unauthenticated, remote attacker to bypass configured policies. The issue is due to a flaw in the detection algorithm. An attacker could send crafted packets through an affected system, potentially bypassing policies and delivering a malicious payload.
Original NVD description (English source)
A vulnerability in the Modbus preprocessor of the Snort detection engine could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to an integer overflow while processing Modbus traffic. An attacker could exploit this vulnerability by sending crafted Modbus traffic through an affected device. A successful exploit could allow the attacker to cause the Snort process to hang, causing traffic inspection to stop.Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

