PatchTheCVECVE-2021-33485: CODESYS Control Runtime system before 3.5.17.10 has a Heap-based Buffer Overflow.
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CRITICAL 9.8REMOTEUPGRADEUPGRADEUPGRADE
CVE-2021-33485 is a critical-severity flaw (CVSS 9.8) affecting control, control, control. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
CODESYS Control Runtime system before 3.5.17.10 has a Heap-based Buffer Overflow.
Why this priority
- Critical severity
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Last updated 2026-06-17 · 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
codesys control UPGRADE
Affected: < 4.2.0.0
Fixed in: 4.2.0.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy control || rpm -q control || control --version
2. UPGRADE to 4.2.0.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade control
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade control
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
codesys control UPGRADE
Affected: < 4.2.0.0
Fixed in: 4.2.0.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy control || rpm -q control || control --version
2. UPGRADE to 4.2.0.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade control
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade control
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
codesys control UPGRADE
Affected: < 4.2.0.0
Fixed in: 4.2.0.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy control || rpm -q control || control --version
2. UPGRADE to 4.2.0.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade control
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade control
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
codesys control UPGRADE
Affected: <= 4.2.0.0
Fixed in: newer than 4.2.0.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy control || rpm -q control || control --version
2. UPGRADE to newer than 4.2.0.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade control
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade control
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
codesys control UPGRADE
Affected: < 4.2.0.0
Fixed in: 4.2.0.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy control || rpm -q control || control --version
2. UPGRADE to 4.2.0.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade control
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade control
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
codesys control UPGRADE
Affected: < 4.2.0.0
Fixed in: 4.2.0.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy control || rpm -q control || control --version
2. UPGRADE to 4.2.0.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade control
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade control
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
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-2021-33485?
control: upgrade to 4.2.0.0; control: upgrade to 4.2.0.0; control: upgrade to 4.2.0.0. Exact commands for each OS are on this page.
Is CVE-2021-33485 being exploited?
CVE-2021-33485 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-2021-33485 affect?
CVE-2021-33485 affects control, control, control. Severity is critical (CVSS 9.8). CODESYS Control Runtime system before 3.5.17.10 has a Heap-based Buffer Overflow.
How urgent is CVE-2021-33485?
Priority 56/100. Critical severity; Remotely exploitable, no login, no user action
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