PatchTheCVECVE-2004-0809: The mod_dav module in Apache 2.0.50 and earlier allows remote attackers to cause a denial of service (child pr
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MEDIUM 5.0WATCHLISTUPGRADEDOWNGRADEMITIGATE
CVE-2004-0809 is a medium-severity flaw (CVSS 5.0) affecting http server, secure web server for tru64, linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
The mod_dav module in Apache 2.0.50 and earlier allows remote attackers to cause a denial of service (child process crash) via a certain sequence of LOCK requests for a location that allows WebDAV authoring access.
Why this priority
- EPSS top 3%: very likely to be exploited
- Public exploit reference
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.0 (Medium) |
| EPSS exploit chance | 17.2% (top 3%) |
| CISA exploited list | No |
| Published | 2004-09-16 |
| Last modified | 2026-06-16 |
Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
apache http server UPGRADE
Affected: >= 2.0.35 and < 2.0.51
Fixed in: 2.0.51
Safe to downgrade to: a release before 2.0.35
1. Check installed version
apt-cache policy http-server || rpm -q http-server || http-server --version
2. UPGRADE to 2.0.51 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade http-server
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade http-server
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 2.0.35 (Debian / Ubuntu)
apt-cache madison http-server
sudo apt install http-server=<VERSION_BEFORE_2.0.35>
sudo apt-mark hold http-server
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list http-server
sudo dnf downgrade http-server-<VERSION_BEFORE_2.0.35>
sudo dnf versionlock add http-server
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.
hp secure web server for tru64 DOWNGRADE
Affected: 4.0_f · 4.0_g · 5.0_a · 5.1 · 5.1_a · 5.8.1 · 5.8.2 · 5.9.1
Fixed in: no fixed release known
Safe to downgrade to: a release before 4.0_f
1. Check installed version
apt-cache policy secure-web-server-for-tru64 || rpm -q secure-web-server-for-tru64 || secure-web-server-for-tru64 --version
2. No fixed release: DOWNGRADE to a release before 4.0_f (Debian / Ubuntu)
apt-cache madison secure-web-server-for-tru64
sudo apt install secure-web-server-for-tru64=<VERSION_BEFORE_4.0_f>
sudo apt-mark hold secure-web-server-for-tru64
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list secure-web-server-for-tru64
sudo dnf downgrade secure-web-server-for-tru64-<VERSION_BEFORE_4.0_f>
sudo dnf versionlock add secure-web-server-for-tru64
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.
gentoo linux MITIGATE
Affected: 1.4
Fixed in: no fixed release known
Safe to downgrade to: a release before 1.4
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
hp hp-ux MITIGATE
Affected: 11.00 · 11.11 · 11.22 · 11.23
Fixed in: no fixed release known
Safe to downgrade to: a release before 11.00
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
mandrakesoft mandrake linux MITIGATE
Affected: 9.2 · 10.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 9.2
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
redhat enterprise linux MITIGATE
Affected: 3.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 3.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
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.
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-2004-0809?
http server: upgrade to 2.0.51; secure web server for tru64: downgrade or apply the listed mitigation; linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2004-0809 being exploited?
CVE-2004-0809 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-2004-0809 affect?
CVE-2004-0809 affects http server, secure web server for tru64, linux. Severity is medium (CVSS 5.0). The mod_dav module in Apache 2.0.50 and earlier allows remote attackers to cause a denial of service (child process crash) via a certain sequence of LOCK requests for a location that allows WebDAV authoring access.
How urgent is CVE-2004-0809?
Priority 52/100. EPSS top 3%: very likely to be exploited; Public exploit reference; On your watchlist
Software pages
Apache HTTP Server vulnerabilities
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