CVE-2025-7673: A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware vers
52
This month
CRITICAL 9.8REMOTEMITIGATEMITIGATEMITIGATE
CVE-2025-7673 is a critical-severity flaw (CVSS 9.8) affecting emg3525-t50b firmware, emg5523-t50b firmware, emg5723-t50k firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware versions prior to V5.50(ABOM.5)C0 could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and potentially execute arbitrary code by sending a specially crafted HTTP request.
Why this priority
Critical severity
Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
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
zyxel emg3525-t50b firmware MITIGATE
Affected: < 5.50\(abpm.4\)c0 · < 5.50\(absl.0\)b8
Fixed in: 5.50\(abpm.4\)c0, 5.50\(absl.0\)b8
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.
zyxel emg5523-t50b firmware MITIGATE
Affected: < 5.50\(abpm.4\)c0 · < 5.50\(absl.0\)b8
Fixed in: 5.50\(abpm.4\)c0, 5.50\(absl.0\)b8
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.
zyxel emg5723-t50k firmware MITIGATE
Affected: < 5.50\(abom.5\)c0
Fixed in: 5.50\(abom.5\)c0
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.
zyxel emg6726-b10a firmware MITIGATE
Affected: < 5.13\(abnp.6\).c
Fixed in: 5.13\(abnp.6\).c
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.
zyxel ex3510-b0 firmware MITIGATE
Affected: < 5.17\(abup.3\)c0
Fixed in: 5.17\(abup.3\)c0
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.
zyxel ex5510-b0 firmware MITIGATE
Affected: < 5.15\(abqx.3\)c0
Fixed in: 5.15\(abqx.3\)c0
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.
Verify at the official sourceNVD · 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-2025-7673?
emg3525-t50b firmware: mitigate or apply the listed mitigation; emg5523-t50b firmware: mitigate or apply the listed mitigation; emg5723-t50k firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2025-7673 being exploited?
CVE-2025-7673 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-2025-7673 affect?
CVE-2025-7673 affects emg3525-t50b firmware, emg5523-t50b firmware, emg5723-t50k firmware. Severity is critical (CVSS 9.8). A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware versions prior to V5.50(ABOM.5)C0 could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and potentially
How urgent is CVE-2025-7673?
Priority 52/100. Critical severity; Remotely exploitable, no login, no user action
CVE-2026-1459HIGH 7.2MITIGATEMITIGATE A post-authentication command injection vulnerability in the TR-369 certificate download CGI program of the Zy
CVE-2023-37929MEDIUM 6.5MITIGATEMITIGATE The buffer overflow vulnerability in the CGI program of the VMG3625-T50B firmware version V5.50(ABPM.8)C0 coul
PatchTheCVE