PatchTheCVECVE-1999-1011: The Remote Data Service (RDS) DataFactory component of Microsoft Data Access Components (MDAC) in IIS 3.x and
70
This week
HIGH 10.0WATCHLISTDOWNGRADEDOWNGRADEDOWNGRADE
CVE-1999-1011 is a high-severity flaw (CVSS 10.0) affecting data access components, index server, internet information server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
The Remote Data Service (RDS) DataFactory component of Microsoft Data Access Components (MDAC) in IIS 3.x and 4.x exposes unsafe methods, which allows remote attackers to execute arbitrary commands.
Why this priority
- Critical severity
- EPSS top 1%: very likely to be exploited
- Public exploit reference
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 10.0 (High) |
| EPSS exploit chance | 77.1% (top 1%) |
| CISA exploited list | No |
| Weakness | CWE-264 |
| Published | 1999-07-19 |
| 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
microsoft data access components DOWNGRADE
Affected: 1.5 · 2.0 · 2.1
Fixed in: no fixed release known
Safe to downgrade to: a release before 1.5
1. Check installed version
apt-cache policy data-access-components || rpm -q data-access-components || data-access-components --version
2. No fixed release: DOWNGRADE to a release before 1.5 (Debian / Ubuntu)
apt-cache madison data-access-components
sudo apt install data-access-components=<VERSION_BEFORE_1.5>
sudo apt-mark hold data-access-components
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list data-access-components
sudo dnf downgrade data-access-components-<VERSION_BEFORE_1.5>
sudo dnf versionlock add data-access-components
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 index server DOWNGRADE
Affected: 2.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.0
1. Check installed version
apt-cache policy index-server || rpm -q index-server || index-server --version
2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)
apt-cache madison index-server
sudo apt install index-server=<VERSION_BEFORE_2.0>
sudo apt-mark hold index-server
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list index-server
sudo dnf downgrade index-server-<VERSION_BEFORE_2.0>
sudo dnf versionlock add index-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.
microsoft internet information server DOWNGRADE
Affected: 3.0 · 4.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 3.0
1. Check installed version
apt-cache policy internet-information-server || rpm -q internet-information-server || internet-information-server --version
2. No fixed release: DOWNGRADE to a release before 3.0 (Debian / Ubuntu)
apt-cache madison internet-information-server
sudo apt install internet-information-server=<VERSION_BEFORE_3.0>
sudo apt-mark hold internet-information-server
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list internet-information-server
sudo dnf downgrade internet-information-server-<VERSION_BEFORE_3.0>
sudo dnf versionlock add internet-information-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.
microsoft site server DOWNGRADE
Affected: 3.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 3.0
1. Check installed version
apt-cache policy site-server || rpm -q site-server || site-server --version
2. No fixed release: DOWNGRADE to a release before 3.0 (Debian / Ubuntu)
apt-cache madison site-server
sudo apt install site-server=<VERSION_BEFORE_3.0>
sudo apt-mark hold site-server
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list site-server
sudo dnf downgrade site-server-<VERSION_BEFORE_3.0>
sudo dnf versionlock add site-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.
Exact fixes by distribution
A distro patch exists: prefer upgrading over downgrading.
Fedora ELN · python-nodeenv · FIXED · 1.12.0-1.eln159 · FEDORA-2026-4081f7f008 · source
sudo dnf upgrade --advisory=FEDORA-2026-4081f7f008
Fedora 46 · udns · FIXED · 0.7-1.fc46 · FEDORA-2026-e747764426 · source
sudo dnf upgrade --advisory=FEDORA-2026-e747764426
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: Microsoft Data Access Components (MDAC) 2.1 / Microsoft IIS 3.0/4.0 / Microsoft Index Server 2.0 / Microsoft Site Server
- Exploit-DB: Microsoft Data Access Components (MDAC) 2.1 / Microsoft IIS 3.0/4.0 / Microsoft Index Server 2.0 / Microsoft Site Server
- Metasploit: MS99-025 Microsoft IIS MDAC msadcs.dll RDS Arbitrary Remote Command Execution
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-1999-1011?
data access components: downgrade or apply the listed mitigation; index server: downgrade or apply the listed mitigation; internet information server: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-1999-1011 being exploited?
CVE-1999-1011 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-1999-1011 affect?
CVE-1999-1011 affects data access components, index server, internet information server. Severity is high (CVSS 10.0). The Remote Data Service (RDS) DataFactory component of Microsoft Data Access Components (MDAC) in IIS 3.x and 4.x exposes unsafe methods, which allows remote attackers to execute arbitrary commands.
How urgent is CVE-1999-1011?
Priority 70/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; On your watchlist
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