CVE-2000-0620: libX11 X library allows remote attackers to cause a denial of service via a resource mask of 0, which causes l

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MEDIUM 5.0DOWNGRADEDOWNGRADE

CVE-2000-0620 is a medium-severity flaw (CVSS 5.0) affecting x, x11r6. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

libX11 X library allows remote attackers to cause a denial of service via a resource mask of 0, which causes libX11 to go into an infinite loop.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	1.7% (top 22%)
CISA exploited list	No
Published	2000-06-19
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: open group · xfree86 project

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

Am I affected?

Timeline

2000-06-19 04:00 UTCPublished CVE record published
2026-06-16 21:52 UTCUpdated Record last modified

open group x DOWNGRADE

Affected: 11.0r6 · 11.0r6.1 · 11.0r6.2 · 11.0r6.3 · 11.0r6.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 11.0r6

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 11.0r6 (Debian / Ubuntu)

apt-cache madison x sudo apt install x=<VERSION_BEFORE_11.0r6> sudo apt-mark hold x

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

dnf --showduplicates list x sudo dnf downgrade x-<VERSION_BEFORE_11.0r6> sudo dnf versionlock add x

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.

xfree86 project x11r6 DOWNGRADE

Affected: 3.3.3 · 3.3.4 · 3.3.5 · 3.3.6 · 4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.3.3

1. Check installed version

apt-cache policy x11r6 || rpm -q x11r6 || x11r6 --version

2. No fixed release: DOWNGRADE to a release before 3.3.3 (Debian / Ubuntu)

apt-cache madison x11r6 sudo apt install x11r6=<VERSION_BEFORE_3.3.3> sudo apt-mark hold x11r6

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

dnf --showduplicates list x11r6 sudo dnf downgrade x11r6-<VERSION_BEFORE_3.3.3> sudo dnf versionlock add x11r6

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-2000-0620?

x: downgrade or apply the listed mitigation; x11r6: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2000-0620 being exploited?

CVE-2000-0620 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-2000-0620 affect?

CVE-2000-0620 affects x, x11r6. Severity is medium (CVSS 5.0). libX11 X library allows remote attackers to cause a denial of service via a resource mask of 0, which causes libX11 to go into an infinite loop.

How urgent is CVE-2000-0620?

Priority 42/100. Public exploit reference

Related CVEs

CVE-2000-0504 MEDIUM 5.0 DOWNGRADE DOWNGRADE libICE in XFree86 allows remote attackers to cause a denial of service by specifying a large value which is no

References

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