CVE-2000-0564: The guestbook CGI program in ICQ Web Front service for ICQ 2000a, 99b, and others allows remote attackers to c

Routine

MEDIUM 5.0DOWNGRADE

CVE-2000-0564 is a medium-severity flaw (CVSS 5.0) affecting icq. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The guestbook CGI program in ICQ Web Front service for ICQ 2000a, 99b, and others allows remote attackers to cause a denial of service via a URL with a long name parameter.

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	1.3% (top 29%)
CISA exploited list	No
Published	2000-05-29
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: mirabilis

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

Am I affected?

Timeline

2000-05-29 04:00 UTCPublished CVE record published
2026-06-16 21:52 UTCUpdated Record last modified

mirabilis icq DOWNGRADE

Affected: 0.99b_1.1.1.1 · 0.99b_v.3.19 · 98.0a · 99a_2.15build1701 · 99a_2.21build1800 · 2000.0a

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.99b_1.1.1.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.99b_1.1.1.1 (Debian / Ubuntu)

apt-cache madison icq sudo apt install icq=<VERSION_BEFORE_0.99b_1.1.1.1> sudo apt-mark hold icq

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

dnf --showduplicates list icq sudo dnf downgrade icq-<VERSION_BEFORE_0.99b_1.1.1.1> sudo dnf versionlock add icq

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-2000-0564?

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

Is CVE-2000-0564 being exploited?

CVE-2000-0564 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-2000-0564 affect?

CVE-2000-0564 affects icq. Severity is medium (CVSS 5.0). The guestbook CGI program in ICQ Web Front service for ICQ 2000a, 99b, and others allows remote attackers to cause a denial of service via a URL with a long name parameter.

How urgent is CVE-2000-0564?

Priority 35/100. No elevated risk signals yet.

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References

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