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CVE-2004-0866: Internet Explorer 6.0 allows web sites to set cookies for country-specific top-level domains, such as .ltd.uk,

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HIGH 7.5WATCHLISTDOWNGRADEDOWNGRADEDOWNGRADE

CVE-2004-0866 is a high-severity flaw (CVSS 7.5) affecting konqueror, ie, internet explorer. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Internet Explorer 6.0 allows web sites to set cookies for country-specific top-level domains, such as .ltd.uk, .plc.uk, and .sch.uk, which could allow remote attackers to perform a session fixation attack and hijack a user's HTTP session.

Why this priority

  • High severity
  • EPSS top 4%: very likely to be exploited
  • On your watchlist

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

Risk facts

CVSS score7.5 (High)
EPSS exploit chance10.1% (top 4%)
CISA exploited listNo
Published2004-09-16
Last modified2026-06-16
Publisher (CNA): MITRE · Vendor: kde · microsoft · mozilla · suse

Share: LinkedIn · X · Reddit

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

Am I affected?

Timeline

kde konqueror DOWNGRADE
Affected: 2.1.1 · 2.1.2 · 2.2.1 · 2.2.2 · 3.0 · 3.0.1 · 3.0.2 · 3.0.3
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.1.1
1. Check installed version
apt-cache policy konqueror || rpm -q konqueror || konqueror --version
2. No fixed release: DOWNGRADE to a release before 2.1.1 (Debian / Ubuntu)
apt-cache madison konqueror sudo apt install konqueror=<VERSION_BEFORE_2.1.1> sudo apt-mark hold konqueror
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list konqueror sudo dnf downgrade konqueror-<VERSION_BEFORE_2.1.1> sudo dnf versionlock add konqueror
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.
microsoft ie DOWNGRADE
Affected: 6.0 sp1 · 6.0 sp2
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.0
1. Check installed version
apt-cache policy ie || rpm -q ie || ie --version
2. No fixed release: DOWNGRADE to a release before 6.0 (Debian / Ubuntu)
apt-cache madison ie sudo apt install ie=<VERSION_BEFORE_6.0> sudo apt-mark hold ie
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list ie sudo dnf downgrade ie-<VERSION_BEFORE_6.0> sudo dnf versionlock add ie
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.
microsoft internet explorer DOWNGRADE
Affected: 6.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.0
1. Check installed version
apt-cache policy internet-explorer || rpm -q internet-explorer || internet-explorer --version
2. No fixed release: DOWNGRADE to a release before 6.0 (Debian / Ubuntu)
apt-cache madison internet-explorer sudo apt install internet-explorer=<VERSION_BEFORE_6.0> sudo apt-mark hold internet-explorer
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list internet-explorer sudo dnf downgrade internet-explorer-<VERSION_BEFORE_6.0> sudo dnf versionlock add internet-explorer
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.
mozilla firefox DOWNGRADE
Affected: 0.9.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 0.9.2
1. Check installed version
apt-cache policy firefox || rpm -q firefox || firefox --version
2. No fixed release: DOWNGRADE to a release before 0.9.2 (Debian / Ubuntu)
apt-cache madison firefox sudo apt install firefox=<VERSION_BEFORE_0.9.2> sudo apt-mark hold firefox
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list firefox sudo dnf downgrade firefox-<VERSION_BEFORE_0.9.2> sudo dnf versionlock add firefox
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.
suse suse linux MITIGATE
Affected: 1.0 · 8 · 8.1 · 8.2 · 9.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 1.0
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.

Quick answers

How do I fix CVE-2004-0866?

konqueror: downgrade or apply the listed mitigation; ie: downgrade or apply the listed mitigation; internet explorer: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2004-0866 being exploited?

CVE-2004-0866 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-2004-0866 affect?

CVE-2004-0866 affects konqueror, ie, internet explorer. Severity is high (CVSS 7.5). Internet Explorer 6.0 allows web sites to set cookies for country-specific top-level domains, such as .ltd.uk, .plc.uk, and .sch.uk, which could allow remote attackers to perform a session fixation attack and hijack a user's HTTP session.

How urgent is CVE-2004-0866?

Priority 55/100. High severity; EPSS top 4%: very likely to be exploited; On your watchlist

Software pages

Mozilla Firefox vulnerabilities · Internet Explorer vulnerabilities

Related CVEs

References

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