How severe is CVE-2018-3955?

CVE-2018-3955 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-3955 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-3955?

CVE-2018-3955 primarily affects Linksys E1200 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-3955?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-3955 published?

CVE-2018-3955 was published on 2018-10-17 and last updated on 2026-06-17.

CVE-2018-3955

CVE-2018-3955 is a high-severity vulnerability in Linksys E1200 Firmware with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v2: 9.0
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Linksys E1200 Firmware
Published: 2018-10-17
Last modified: 2026-06-17

Description

An exploitable operating system command injection exists in the Linksys ESeries line of routers (Linksys E1200 Firmware Version 2.0.09 and Linksys E2500 Firmware Version 3.0.04). Specially crafted entries to network configuration information can cause execution of arbitrary system commands, resulting in full control of the device. An attacker can send an authenticated HTTP request to trigger this vulnerability. Data entered into the 'Domain Name' input field through the web portal is submitted to apply.cgi as the value to the 'wan_domain' POST parameter. The wan_domain data goes through the nvram_set process described above. When the 'preinit' binary receives the SIGHUP signal it enters a code path that calls a function named 'set_host_domain_name' from its libshared.so shared object.

Frequently asked questions

What is CVE-2018-3955?: An exploitable operating system command injection exists in the Linksys ESeries line of routers (Linksys E1200 Firmware Version 2.0.09 and Linksys E2500 Firmware Version 3.0.04). Specially crafted entries to network configuration information can cause execution of arbitrary system commands, resulting in full control of the device. An attacker can send an authenticated HTTP request to trigger this vulnerability. Data entered into the 'Domain Name' input field through the web portal is submitted to apply.cgi as the value to the 'wan_domain' POST parameter. The wan_domain data goes through the nvram_set process described above. When the 'preinit' binary receives the SIGHUP signal it enters a code path that calls a function named 'set_host_domain_name' from its libshared.so shared object.
How severe is CVE-2018-3955?: CVE-2018-3955 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-3955 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-3955?: CVE-2018-3955 primarily affects Linksys E1200 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-3955?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-3955 published?: CVE-2018-3955 was published on 2018-10-17 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2018-0625

Affected products (2)

cpe:2.3:o:linksys:e1200_firmware:2.0.09:*:*:*:*:*:*:*
cpe:2.3:o:linksys:e2500_firmware:3.0.04:*:*:*:*:*:*:*

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