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CVE-2026-20019— Multiple Cisco Products Snort 3 Netflow Denial of Service Vulnerabilities

Quick assessment

Affected
Cisco Cisco Open Source Snort3
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

思科多款产品受 Snort 3 NetFlow 检测引擎中一个漏洞的影响。该漏洞可能使未经身份验证的远程攻击者触发 Snort 3 检测引擎重启，从而导致数据包检测服务中断。 此漏洞源于 Snort 3 在解析 UDP NetFlow 协议数据包时存在不完整的错误检查。攻击者可通过已建立的连接向 Snort 3 发送单个精心构造的 NetFlow 数据包来利用该漏洞。一旦成功利用，攻击者即可导致 Snort 3 检测引擎意外重启，进而引发拒绝服务（DoS）状况。

CVSS 5.8 · Medium

Possible ATT&CK Techniques 1 AI

T1499.001 · OS Exhaustion Flood

Affected Version Matrix 203

VendorProduct Version RangeStatus
Cisco Cisco Open Source Snort3 3.12.2.0 affected
3.1.2.0 affected
3.1.3.0 affected
3.1.4.0 affected
3.1.5.0 affected
3.1.6.0 affected
3.1.7.0 affected
3.1.8.0 affected
… +97 more rows
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 affected
7.0.0.1 affected
7.0.1 affected
7.0.1.1 affected
7.0.2 affected
7.2.0 affected
7.0.2.1 affected
7.0.3 affected
… +52 more rows
Cisco Cisco UTD SNORT IPS Engine Software 17.12.1a affected
17.12.2 affected
17.13.1a affected
17.12.3 affected
17.14.1a affected
17.12.4 affected
17.12.3a affected
17.15.1a affected
… +30 more rows
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I. Basic Information for CVE-2026-20019

Vulnerability Information
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Vulnerability Title
Multiple Cisco Products Snort 3 Netflow Denial of Service Vulnerabilities
Source: CVE Program / CVE List V5
Vulnerability Description
Multiple Cisco products are affected by a vulnerability in the Snort 3 NetFlow 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 UDP Netflow Protocol packets. An attacker could exploit this vulnerability by sending a single crafted Netflow packet through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
不可达退出条件的循环(无限循环)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cisco Cisco Open Source Snort3 3.12.2.0 -
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 -
Cisco Cisco UTD SNORT IPS Engine Software 17.12.1a -

II. Public POCs for CVE-2026-20019

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III. Intelligence Information for CVE-2026-20019

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Other References for CVE-2026-20019 (1)

Same Patch Batch · Cisco · 2026-10-21 · 34 CVEs total

CVE-2026-76466 9.8 CRITICAL Cisco Expressway Series Remote Code Execution Vulnerability
CVE-2026-76473 9.8 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Improper control o
CVE-2026-76474 9.8 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Improper Authentic
CVE-2026-76475 9.3 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Cross-site Scripti
CVE-2026-20043 9.0 CRITICAL Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76477 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Injection Vulnerab
CVE-2026-76476 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Input Val
CVE-2026-76478 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Access Co
CVE-2026-76490 8.6 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Out-of-bounds Write Vul
CVE-2026-76524 7.8 HIGH Open Source Snort 3 Control Channel Socket Aribitrary Command Execution Vulnerability
CVE-2026-20291 7.8 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76479 7.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Path Traversal Vul
CVE-2026-76494 7.8 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Code Injection Vulnerab
CVE-2026-76495 7.8 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Incorrect Permission As
CVE-2026-76481 7.5 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Check or
CVE-2026-76491 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Denial of Service Vulne
CVE-2026-76492 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - NULL Pointer Vulnerabil
CVE-2026-76505 7.5 HIGH Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service V
CVE-2026-76493 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Uncaught Exception Vuln
CVE-2026-20236 7.5 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026

Showing top 20 of 34 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Cisco Open Source Snort3
Same vendor: Cisco
Same weakness: CWE-835

V. Comments for CVE-2026-20019

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