CVE-2002-1747: Vtun 2.5b1 does not authenticate forwarded packets, which allows remote attackers to inject data into user ses

Routine

MEDIUM 5.0DOWNGRADE

CVE-2002-1747 is a medium-severity flaw (CVSS 5.0) affecting vtun. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vtun 2.5b1 does not authenticate forwarded packets, which allows remote attackers to inject data into user sessions without detection, and possibly control the data contents via cut-and-paste attacks on ECB.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	1.1% (top 35%)
CISA exploited list	No
Published	2002-12-31
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: maxim krasnyansky

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

Am I affected?

Timeline

2002-12-31 05:00 UTCPublished CVE record published
2026-06-16 21:59 UTCUpdated Record last modified

maxim krasnyansky vtun DOWNGRADE

Affected: 2.5b1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.5b1

1. Check installed version

apt-cache policy vtun || rpm -q vtun || vtun --version

2. No fixed release: DOWNGRADE to a release before 2.5b1 (Debian / Ubuntu)

apt-cache madison vtun sudo apt install vtun=<VERSION_BEFORE_2.5b1> sudo apt-mark hold vtun

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

dnf --showduplicates list vtun sudo dnf downgrade vtun-<VERSION_BEFORE_2.5b1> sudo dnf versionlock add vtun

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-2002-1747?

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

Is CVE-2002-1747 being exploited?

CVE-2002-1747 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-2002-1747 affect?

CVE-2002-1747 affects vtun. Severity is medium (CVSS 5.0). Vtun 2.5b1 does not authenticate forwarded packets, which allows remote attackers to inject data into user sessions without detection, and possibly control the data contents via cut-and-paste attacks on ECB.

How urgent is CVE-2002-1747?

Priority 34/100. No elevated risk signals yet.

Related CVEs

CVE-2002-1746 MEDIUM 5.0 DOWNGRADE Vtun 2.5b1 allows remote attackers to inject data into user sessions by sniffing and replaying packets.
CVE-2002-1697 HIGH 7.5 UPGRADE Electronic Code Book (ECB) mode in VTun 2.0 through 2.5 uses a weak encryption algorithm that produces the sam

References

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