CVE-2018-3953

high-risk
Published 2018-10-17

Devices in the Linksys ESeries line of routers (Linksys E1200 Firmware Version 2.0.09 and Linksys E2500 Firmware Version 3.0.04) are susceptible to OS command injection vulnerabilities due to improper filtering of data passed to and retrieved from NVRAM. Data entered into the 'Router Name' input field through the web portal is submitted to apply.cgi as the value to the 'machine_name' POST parameter. When the 'preinit' binary receives the SIGHUP signal, it enters a code path that continues until it reaches offset 0x0042B5C4 in the 'start_lltd' function. Within the 'start_lltd' function, a 'nvram_get' call is used to obtain the value of the user-controlled 'machine_name' NVRAM entry. This value is then entered directly into a command intended to write the host name to a file and subsequently executed.

Do I need to act?

!
68.5% chance of exploitation in next 30 days
EPSS score — higher than 32% of all CVEs
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.2/10 High
NETWORK / LOW complexity

Affected Products (2)

E1200 Firmware
E2500 Firmware

Affected Vendors

Linksys

References (2)

Exploit https://talosintelligence.com/vulnerability_reports/TALOS-2018-0625
Exploit https://talosintelligence.com/vulnerability_reports/TALOS-2018-0625
52
/ 100
high-risk
Severity 26/34 · High
Exploitability 19/34 · Moderate
Exposure 7/34 · Low