CVE-2001-1377: Multiple RADIUS implementations do not properly validate the Vendor-Length of the Vendor-Specific attribute, w

This month

MEDIUM 5.0DOWNGRADEDOWNGRADEDOWNGRADE

CVE-2001-1377 is a medium-severity flaw (CVSS 5.0) affecting freeradius, radius, icradius. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Multiple RADIUS implementations do not properly validate the Vendor-Length of the Vendor-Specific attribute, which allows remote attackers to cause a denial of service (crash) via a Vendor-Length that is less than 2.

Why this priority

EPSS top 7%: very likely to be exploited

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	5.4% (top 7%)
CISA exploited list	No
Published	2002-03-04
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: freeradius · gnu · icradius · livingston · lucent · miquel van smoorenburg cistron

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

Am I affected?

Timeline

2002-03-04 05:00 UTCPublished CVE record published
2026-06-16 21:56 UTCUpdated Record last modified

freeradius freeradius DOWNGRADE

Affected: 0.2 · 0.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.2 (Debian / Ubuntu)

apt-cache madison freeradius sudo apt install freeradius=<VERSION_BEFORE_0.2> sudo apt-mark hold freeradius

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

dnf --showduplicates list freeradius sudo dnf downgrade freeradius-<VERSION_BEFORE_0.2> sudo dnf versionlock add freeradius

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.

gnu radius DOWNGRADE

Affected: 0.92.1 · 0.93 · 0.94 · 0.95

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.92.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.92.1 (Debian / Ubuntu)

apt-cache madison radius sudo apt install radius=<VERSION_BEFORE_0.92.1> sudo apt-mark hold radius

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

dnf --showduplicates list radius sudo dnf downgrade radius-<VERSION_BEFORE_0.92.1> sudo dnf versionlock add radius

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.

icradius icradius DOWNGRADE

Affected: 0.14 · 0.15 · 0.16 · 0.17 · 0.17b · 0.18 · 0.18.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.14

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.14 (Debian / Ubuntu)

apt-cache madison icradius sudo apt install icradius=<VERSION_BEFORE_0.14> sudo apt-mark hold icradius

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

dnf --showduplicates list icradius sudo dnf downgrade icradius-<VERSION_BEFORE_0.14> sudo dnf versionlock add icradius

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.

livingston radius DOWNGRADE

Affected: 2.0 · 2.0.1 · 2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

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

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

dnf --showduplicates list radius sudo dnf downgrade radius-<VERSION_BEFORE_2.0> sudo dnf versionlock add radius

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.

lucent radius DOWNGRADE

Affected: 2.0 · 2.0.1 · 2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

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

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

dnf --showduplicates list radius sudo dnf downgrade radius-<VERSION_BEFORE_2.0> sudo dnf versionlock add radius

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.

miquel van smoorenburg cistron radius DOWNGRADE

Affected: 1.6.1 · 1.6.2 · 1.6.3 · 1.6.4 · 1.6.5 · 1.6_.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.6_.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.6_.0 (Debian / Ubuntu)

apt-cache madison radius sudo apt install radius=<VERSION_BEFORE_1.6_.0> sudo apt-mark hold radius

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

dnf --showduplicates list radius sudo dnf downgrade radius-<VERSION_BEFORE_1.6_.0> sudo dnf versionlock add radius

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-2001-1377?

freeradius: downgrade or apply the listed mitigation; radius: downgrade or apply the listed mitigation; icradius: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2001-1377 being exploited?

CVE-2001-1377 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-2001-1377 affect?

CVE-2001-1377 affects freeradius, radius, icradius. Severity is medium (CVSS 5.0). Multiple RADIUS implementations do not properly validate the Vendor-Length of the Vendor-Specific attribute, which allows remote attackers to cause a denial of service (crash) via a Vendor-Length that is less than 2.

How urgent is CVE-2001-1377?

Priority 41/100. EPSS top 7%: very likely to be exploited

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References

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