CVE-2002-1697: Electronic Code Book (ECB) mode in VTun 2.0 through 2.5 uses a weak encryption algorithm that produces the sam

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HIGH 7.5REMOTEUPGRADE

CVE-2002-1697 is a high-severity flaw (CVSS 7.5) affecting vtun. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Electronic Code Book (ECB) mode in VTun 2.0 through 2.5 uses a weak encryption algorithm that produces the same ciphertext from the same plaintext blocks, which could allow remote attackers to gain sensitive information.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 42%)
CISA exploited list	No
Weakness	CWE-326
Published	2002-12-31
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: vtun project

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

vtun project vtun UPGRADE

Affected: >= 2.0 and <= 2.5

Fixed in: newer than 2.5

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. UPGRADE to newer than 2.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade vtun

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade vtun

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

apt-cache madison vtun sudo apt install vtun=<VERSION_BEFORE_2.0> sudo apt-mark hold vtun

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list vtun sudo dnf downgrade vtun-<VERSION_BEFORE_2.0> 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-2002-1697?

vtun: upgrade to newer than 2.5. Exact commands for each OS are on this page.

Is CVE-2002-1697 being exploited?

CVE-2002-1697 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-2002-1697 affect?

CVE-2002-1697 affects vtun. Severity is high (CVSS 7.5). Electronic Code Book (ECB) mode in VTun 2.0 through 2.5 uses a weak encryption algorithm that produces the same ciphertext from the same plaintext blocks, which could allow remote attackers to gain sensitive information.

How urgent is CVE-2002-1697?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2002-1747 MEDIUM 5.0 DOWNGRADE Vtun 2.5b1 does not authenticate forwarded packets, which allows remote attackers to inject data into user ses
CVE-2002-1746 MEDIUM 5.0 DOWNGRADE Vtun 2.5b1 allows remote attackers to inject data into user sessions by sniffing and replaying packets.

References

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