PatchTheCVECVE-2023-35921: A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions
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HIGH 7.5REMOTEUPGRADEUPGRADEUPGRADE
CVE-2023-35921 is a high-severity flaw (CVSS 7.5) affecting simatic mv540 h firmware, simatic mv540 s firmware, simatic mv550 h firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). Affected devices cannot properly process specially crafted Ethernet frames sent to the devices. This could allow an unauthenticated remote attacker to cause a denial
Why this priority
- High severity
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.9% (top 42%) |
| CISA exploited list | No |
| Weakness | CWE-400 |
| Published | 2023-07-11 |
| Last modified | 2026-10-23 |
Publisher (CNA): Siemens AG · Vendor: siemens
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
siemens simatic mv540 h firmware UPGRADE
Affected: < 3.3.4
Fixed in: 3.3.4
Safe to downgrade to: no unaffected older release
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.
siemens simatic mv540 s firmware UPGRADE
Affected: < 3.3.4
Fixed in: 3.3.4
Safe to downgrade to: no unaffected older release
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.
siemens simatic mv550 h firmware UPGRADE
Affected: < 3.3.4
Fixed in: 3.3.4
Safe to downgrade to: no unaffected older release
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.
siemens simatic mv550 s firmware UPGRADE
Affected: < 3.3.4
Fixed in: 3.3.4
Safe to downgrade to: no unaffected older release
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.
siemens simatic mv560 u firmware UPGRADE
Affected: < 3.3.4
Fixed in: 3.3.4
Safe to downgrade to: no unaffected older release
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.
siemens simatic mv560 x firmware UPGRADE
Affected: < 3.3.4
Fixed in: 3.3.4
Safe to downgrade to: no unaffected older release
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.
Exact fixes by distribution
Fedora 46 · rubygem-eventmachine · FIXED · 1.2.7-37.fc46 · FEDORA-2026-7194c202a2 · source
sudo dnf upgrade --advisory=FEDORA-2026-7194c202a2
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.
Related CVEs
- CVE-2023-36521 HIGH 8.6 UPGRADE UPGRADE A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions
- CVE-2023-35920 HIGH 7.5 UPGRADE UPGRADE A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions