CVE-2021-25811
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST...
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST listen_http_lan parameter. Upon subsequent device restarts after this vulnerability is exploted the device will not be able to access the webserver unless the listen_http_lan parameter to uhttpd.json is manually fixed.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST listen_http_lan parameter. Upon subsequent device restarts after this vulnerability is exploted the device will not be able to access the webserver unless the listen_http_lan parameter to uhttpd.json is manually fixed.
- Record
CVE-2021-25811- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 7.8 High
AV:N/AC:L/Au:N/C:N/I:N/A:C - Updated
- 2026-11-02
CVE List No score
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST listen_http_lan parameter. Upon subsequent device restarts after this vulnerability is exploted the device will not be able to access the webserver unless the listen_http_lan parameter to uhttpd.json is manually fixed.
- Record
CVE-2021-25811- Updated
- 2026-11-02
EUVDEUVD-2021-12694 No score
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST listen_http_lan parameter. Upon subsequent device restarts after this vulnerability is exploted the device will not be able to access the webserver unless the listen_http_lan parameter to uhttpd.json is manually fixed.
- Record
EUVD-2021-12694- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-575x-p9rr-ph24 No score
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST...
MERCUSYS Mercury X18G 1.0.5 devices allow Denial of service via a crafted value to the POST listen_http_lan parameter. Upon subsequent device restarts after this vulnerability is exploted the device will not be able to access the webserver unless the listen_http_lan parameter to uhttpd.json is manually fixed.
- Record
GHSA-575x-p9rr-ph24- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-25811 is a high vulnerability (CVSS 7.5) in Mercusys Mercury X18g Firmware, published April 29, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.63%, the 76th percentile. No source names a fixed version.