CVE-2001-0173: Buffer overflow in qDecoder library 5.08 and earlier, as used in CrazyWWWBoard, CrazySearch, and other CGI pro

This week

HIGH 10.0DOWNGRADEDOWNGRADE

CVE-2001-0173 is a high-severity flaw (CVSS 10.0) affecting crazywwwboard, qdecoder. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer overflow in qDecoder library 5.08 and earlier, as used in CrazyWWWBoard, CrazySearch, and other CGI programs, allows remote attackers to execute arbitrary commands via a long MIME Content-Type header.

Why this priority

Critical severity
EPSS top 7%: very likely to be exploited
Public exploit reference

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

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	6.0% (top 7%)
CISA exploited list	No
Published	2001-05-03
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: nobreak technologies · qdecoder

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

Am I affected?

Timeline

2001-05-03 04:00 UTCPublished CVE record published
2026-06-16 21:53 UTCUpdated Record last modified

nobreak technologies crazywwwboard DOWNGRADE

Affected: 3.0.1 · 98 · 98pe · 2000.0lepx · 2000.0px · 2000lepx · 2000px

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.0.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.0.1 (Debian / Ubuntu)

apt-cache madison crazywwwboard sudo apt install crazywwwboard=<VERSION_BEFORE_3.0.1> sudo apt-mark hold crazywwwboard

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

dnf --showduplicates list crazywwwboard sudo dnf downgrade crazywwwboard-<VERSION_BEFORE_3.0.1> sudo dnf versionlock add crazywwwboard

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.

qdecoder qdecoder DOWNGRADE

Affected: 4.0 · 4.0.1 · 4.3 · 4.3.1 · 5.0 · 5.0.1 · 5.0.2 · 5.0.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

apt-cache madison qdecoder sudo apt install qdecoder=<VERSION_BEFORE_4.0> sudo apt-mark hold qdecoder

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

dnf --showduplicates list qdecoder sudo dnf downgrade qdecoder-<VERSION_BEFORE_4.0> sudo dnf versionlock add qdecoder

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: qDecoder 4.x/5.x - Remote Buffer Overflow

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-2001-0173?

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

Is CVE-2001-0173 being exploited?

CVE-2001-0173 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-2001-0173 affect?

CVE-2001-0173 affects crazywwwboard, qdecoder. Severity is high (CVSS 10.0). Buffer overflow in qDecoder library 5.08 and earlier, as used in CrazyWWWBoard, CrazySearch, and other CGI programs, allows remote attackers to execute arbitrary commands via a long MIME Content-Type header.

How urgent is CVE-2001-0173?

Priority 63/100. Critical severity; EPSS top 7%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2001-1457 HIGH 7.5 DOWNGRADE Buffer overflow in CrazyWWWBoard 2000p4 and 2000LEp5 allows remote attackers to execute arbitrary code via a l

References

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