Cisco Open Source Snort3 GRE Detection Engine input validation

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.5$0-$5k1.54+

Summaryinfo

A vulnerability classified as critical has been found in Cisco Open Source Snort3, Secure Firewall Threat Defense Software and UTD SNORT IPS Engine Software. Affected is an unknown function of the component GRE Detection Engine. This manipulation causes input validation. This vulnerability is registered as CVE-2026-20179. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Cisco Open Source Snort3, Secure Firewall Threat Defense Software and UTD SNORT IPS Engine Software (version now known) and classified as critical. Affected by this vulnerability is some unknown processing of the component GRE Detection Engine. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect availability. The summary by CVE is:

Multiple Cisco products are affected by a vulnerability in the Snort 3 Generic Routing Encapsulation (GRE) 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 Snort 3 parses GRE packets. An attacker could exploit this vulnerability by sending a crafted GRE packet to a targeted device to be parsed by Snort. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2026-20179 since 10/08/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. 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).

Upgrading eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.7
VulDB Meta Temp Score: 6.5

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.8
CNA Vector (cisco): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

10/08/2025 CVE reserved
10/21/2026 +378 days Advisory disclosed
10/21/2026 +0 days VulDB entry created
10/21/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: cisco.com

Advisory: sec.cloudapps.cisco.com
Status: Confirmed

CVE: CVE-2026-20179 (🔒)
GCVE (CVE): GCVE-0-2026-20179
GCVE (VulDB): GCVE-100-424885

Entryinfo

Created: 10/21/2026 18:46
Changes: 10/21/2026 18:46 (27), 10/21/2026 18:47 (37)
Complete: 🔍
Cache ID: 216::103

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