CVE Intelligence
Medium

CVE-2026-20065 — Multiple Cisco Products Snort 3 TBD Denial of Service Vulnerability

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 binder module initialization logic of the Snort Detection Engine. An attacker could exploit this vulnerability by sending certain 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.

Published Mar 4, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: cisco

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.4% (30-day exploitation probability)+5
  • Technical severity (medium)+3
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.38%
ahead of 30% of scored CVEs · Oct 15, 2026
Affects
Cisco
Cisco Secure Firewall Threat Defense (FTD) Software and 4 more
CVSS base
5.8
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Cisco Cisco Secure Firewall Threat Defense (FTD) Software, Cisco Cisco UTD SNORT IPS Engine Software, Cisco Secure Firewall Threat Defense…).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Cisco Cisco Secure Firewall Threat Defense (FTD) Software version 7.0.0version 7.0.0.1version 7.0.1version 7.1.0version 7.0.1.1version 7.1.0.1version 7.0.2version 7.2.0
and 42 more version 7.0.2.1version 7.0.3version 7.1.0.2version 7.2.0.1version 7.0.4version 7.2.1version 7.0.5version 7.3.0version 7.2.2version 7.2.3version 7.3.1version 7.1.0.3version 7.2.4version 7.0.6version 7.2.5version 7.2.4.1version 7.3.1.1version 7.4.0version 7.0.6.1version 7.2.5.1version 7.4.1version 7.2.6version 7.0.6.2version 7.4.1.1version 7.2.7version 7.2.5.2version 7.3.1.2version 7.2.8version 7.6.0version 7.4.2version 7.2.8.1version 7.0.6.3version 7.4.2.1version 7.2.9version 7.0.7version 7.4.2.2version 7.2.10version 7.4.2.3version 7.0.8version 7.0.8.1version 7.4.2.4version 7.2.10.2
Vulnerable CVE Program (cve.org) e CISA ADP
Cisco Cisco UTD SNORT IPS Engine Software version 17.3.1aversion 17.2.1rversion 17.3.2version 17.4.1aversion 17.5.1version 17.3.3version 17.5.1aversion 17.3.4
and 63 more version 17.3.4aversion 17.4.2version 17.4.1bversion 17.6.1aversion 17.7.1aversion 17.6.2version 17.8.1aversion 17.3.5version 17.6.3version 17.6.3aversion 17.7.2version 17.9.1aversion 17.6.4version 17.10.1aversion 17.3.6version 17.3.7version 17.9.2aversion 17.6.5version 17.11.1aversion 17.9.3aversion 17.12.1aversion 17.9.4version 17.6.6version 17.3.8version 17.3.8aversion 17.6.6aversion 17.9.4aversion 17.12.2version 17.13.1aversion 17.9.5aversion 17.12.3version 17.6.7version 17.14.1aversion 17.12.4version 17.12.3aversion 17.15.1aversion 17.6.8version 17.9.6version 17.6.8aversion 17.16.1aversion 17.9.5eversion 17.12.4aversion 17.15.2cversion 17.9.5fversion 17.12.4bversion 17.15.2aversion 17.12.5version 17.17.1version 17.12.5aversion 17.9.7aversion 17.15.3aversion 17.15.3version 17.12.5bversion 17.12.5cversion 17.15.4version 17.9.7bversion 17.18.1version 17.18.1aversion 17.12.6version 17.9.8version 17.15.4cversion 17.12.5dversion 17.18.2
Vulnerable CVE Program (cve.org) e CISA ADP
Cisco Secure Firewall Threat Defense version 7.0.0version 7.0.0.1version 7.0.1version 7.0.1.1version 7.0.2version 7.0.2.1version 7.0.3version 7.0.4
and 42 more version 7.0.5version 7.0.6version 7.0.6.1version 7.0.6.2version 7.0.6.3version 7.0.7version 7.0.8version 7.0.8.1version 7.1.0version 7.1.0.1version 7.1.0.2version 7.1.0.3version 7.2.0version 7.2.0.1version 7.2.1version 7.2.2version 7.2.3version 7.2.4version 7.2.4.1version 7.2.5version 7.2.5.1version 7.2.5.2version 7.2.6version 7.2.7version 7.2.8version 7.2.8.1version 7.2.9version 7.2.10version 7.2.10.2version 7.3.0version 7.3.1version 7.3.1.1version 7.3.1.2version 7.4.0version 7.4.1version 7.4.1.1version 7.4.2version 7.4.2.1version 7.4.2.2version 7.4.2.3version 7.4.2.4version 7.6.0
Vulnerable NIST National Vulnerability Database
Cisco Snort ≥ 3.0.0-233 and < 3.6.3.0 Vulnerable NIST National Vulnerability Database
Cisco Unified Threat Defense Snort Intrusion Prevention System Engine version 17.5.1aversion 17.6.1aversion 17.6.2version 17.6.3version 17.6.3aversion 17.6.4version 17.6.5version 17.6.6
and 63 more version 17.6.6aversion 17.6.7version 17.6.8version 17.6.8aversion 17.7.1aversion 17.7.2version 17.8.1aversion 17.9.1aversion 17.9.2aversion 17.9.3aversion 17.9.4version 17.9.4aversion 17.9.5aversion 17.9.5eversion 17.9.5fversion 17.9.6version 17.9.7aversion 17.9.7bversion 17.9.8version 17.10.1aversion 17.11.1aversion 17.12.1aversion 17.12.2version 17.12.3version 17.12.3aversion 17.12.4version 17.12.4aversion 17.12.4bversion 17.12.5version 17.12.5aversion 17.12.5bversion 17.12.5cversion 17.12.5dversion 17.12.6version 17.13.1aversion 17.14.1aversion 17.15.1aversion 17.15.2aversion 17.15.2cversion 17.15.3version 17.15.3aversion 17.15.4version 17.15.4cversion 17.16.1aversion 17.17.1version 17.18.1version 17.18.1aversion 17.18.2version 17.2.1rversion 17.3.1aversion 17.3.2version 17.3.3version 17.3.4version 17.3.4aversion 17.3.5version 17.3.6version 17.3.7version 17.3.8version 17.3.8aversion 17.4.1aversion 17.4.1bversion 17.4.2version 17.5.1
Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.8 CVSS 3.1 Medium 3.9 1.4 psirt@cisco.com via NIST National Vulnerability Database
5.8 CVSS 3.1 Medium — — cisco via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-667

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.38%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · cisco/cisco secure firewall threat defense (ftd) software, cisco/cisco utd snort ips engine software
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 5.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Mar 4, 2026 · cisco

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

Elsewhere on this site

Cisco
every CVE for this vendor
CWE-667
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-20336 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Resource Lifetime Management Vulnerabilities 29d
  • CVE-2026-20335 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Incorrect Calculation Vulnerabilities 29d
  • CVE-2026-20333 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Incorrect Comparison Vulnerabilities 29d
  • CVE-2026-20323 Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Unauthorized Authentication Bypass Vulnerability 29d
  • CVE-2026-20332 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Improper Access Control Vulnerabilities 29d
  • CVE-2026-20334 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Coding Standards Vulnerabilities 29d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20065 is "Multiple Cisco Products Snort 3 TBD Denial of Service Vulnerability", rated Medium. It affects Cisco Secure Firewall Threat Defense (FTD) Software (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.8 describes technical severity. EPSS 0.38% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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