CVE-2026-20007: A vulnerability in the Snort 2 and Snort 3 deep packet inspection of Cisco Secure Firewall Threat Defense (FTD

Routine

MEDIUM 5.8REMOTEDOWNGRADE

CVE-2026-20007 is a medium-severity flaw (CVSS 5.8) affecting secure firewall threat defense. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in the Snort 2 and Snort 3 deep packet inspection of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured Snort rules and allow traffic onto the network that should have been dropped. This vulnerability is due to a logic error in the integration of the Snort Engine rules with Cisco Secure FTD Software that could allow different Snort rules to be hit when deep i

Why this priority

Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.8 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-284
Published	2026-03-04
Last modified	2026-08-20

Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

Last updated 2026-08-20 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-04 18:16 UTCPublished CVE record published
2026-08-20 16:42 UTCUpdated Record last modified

cisco secure firewall threat defense DOWNGRADE

Affected: 6.4.0 · 6.4.0.1 · 6.4.0.2 · 6.4.0.3 · 6.4.0.4 · 6.4.0.5 · 6.4.0.6 · 6.4.0.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.4.0

1. Check installed version

apt-cache policy secure-firewall-threat-defense || rpm -q secure-firewall-threat-defense || secure-firewall-threat-defense --version

2. No fixed release: DOWNGRADE to a release before 6.4.0 (Debian / Ubuntu)

apt-cache madison secure-firewall-threat-defense sudo apt install secure-firewall-threat-defense=<VERSION_BEFORE_6.4.0> sudo apt-mark hold secure-firewall-threat-defense

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list secure-firewall-threat-defense sudo dnf downgrade secure-firewall-threat-defense-<VERSION_BEFORE_6.4.0> sudo dnf versionlock add secure-firewall-threat-defense

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-20007?

secure firewall threat defense: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-20007 being exploited?

CVE-2026-20007 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-20007 affect?

CVE-2026-20007 affects secure firewall threat defense. Severity is medium (CVSS 5.8). A vulnerability in the Snort 2 and Snort 3 deep packet inspection of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured Snort rules and allow traffic onto the network tha

How urgent is CVE-2026-20007?

Priority 29/100. Remotely exploitable, no login, no user action

Software pages

Cisco vulnerabilities · Suricata and Snort vulnerabilities

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References

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