Cisco Open Source Snort3 Detection Engine infinite loop

Summaryinfo

A vulnerability, which was classified as critical, has been found in Cisco Open Source Snort3, Secure Firewall Threat Defense Software and UTD SNORT IPS Engine Software. This issue affects some unknown processing of the component Detection Engine. The manipulation leads to infinite loop. This vulnerability is documented as CVE-2026-76445. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Cisco Open Source Snort3, Secure Firewall Threat Defense Software and UTD SNORT IPS Engine Software (affected version unknown). This issue affects an unknown functionality of the component Detection Engine. The manipulation with an unknown input leads to a infinite loop vulnerability. Using CWE to declare the problem leads to CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Impacted is availability. The summary by CVE is:

Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the detection engine to unexpectedly restart, resulting in a denial of service (DoS) condition. The vulnerability is due to a flaw in logic handling when General Packet Radio Service (GPRS) Tunneling Protocol (GTP) extension headers are processed within the codec. An attacker could exploit this vulnerability by sending a crafted, fragmented UDP datagram that contains these headers to the Snort 3 Detection Engine of an affected device. A successful exploit could allow the attacker to cause the detection engine to enter an infinite loop, resulting in a DoS condition.

The advisory is shared at sec.cloudapps.cisco.com. The identification of this vulnerability is CVE-2026-76445 since 08/19/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/21/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Firewall Software

Vendor

• Cisco

Name

• Open Source Snort3
• Secure Firewall Threat Defense Software
• UTD SNORT IPS Engine Software

License

• commercial

Website

• Vendor: https://www.cisco.com/

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