CVE-2001-1549: Tiny Personal Firewall 1.0 and 2.0 allows local users to bypass filtering via non-standard TCP packets created

Routine

LOW 2.1DOWNGRADE

CVE-2001-1549 is a low-severity flaw (CVSS 2.1) affecting tiny personal firewall. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Tiny Personal Firewall 1.0 and 2.0 allows local users to bypass filtering via non-standard TCP packets created with non-Windows protocol adapters.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	2.1 (Low)
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Published	2001-12-31
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: tiny software

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2001-12-31 05:00 UTCPublished CVE record published
2026-06-16 21:56 UTCUpdated Record last modified

tiny software tiny personal firewall DOWNGRADE

Affected: 1.0 · 2.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

apt-cache policy tiny-personal-firewall || rpm -q tiny-personal-firewall || tiny-personal-firewall --version

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison tiny-personal-firewall sudo apt install tiny-personal-firewall=<VERSION_BEFORE_1.0> sudo apt-mark hold tiny-personal-firewall

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

dnf --showduplicates list tiny-personal-firewall sudo dnf downgrade tiny-personal-firewall-<VERSION_BEFORE_1.0> sudo dnf versionlock add tiny-personal-firewall

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: ZoneAlarm Pro 1.0/2.x - Outbound Packet Bypass

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-2001-1549?

tiny personal firewall: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2001-1549 being exploited?

CVE-2001-1549 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-2001-1549 affect?

CVE-2001-1549 affects tiny personal firewall. Severity is low (CVSS 2.1). Tiny Personal Firewall 1.0 and 2.0 allows local users to bypass filtering via non-standard TCP packets created with non-Windows protocol adapters.

How urgent is CVE-2001-1549?

Priority 26/100. Public exploit reference

Software pages

Windows vulnerabilities

Related CVEs

CVE-2002-1925 MEDIUM 5.0 DOWNGRADE Tiny Personal Firewall 3.0 through 3.0.6 allows remote attackers to cause a denial of service (crash) by via S
CVE-2002-0349 MEDIUM 4.6 DOWNGRADE Tiny Personal Firewall (TPF) 2.0.15, under certain configurations, will pop up an alert to the system even whe

References

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