Summary
A critical command-injection vulnerability in the Linksys E1700's setLinksysIpv6 function allows crafted IPv6 6rd configuration values to influence operating-system command execution.
Because the affected /goform/setLinksysIpv6 endpoint can be reached remotely, an attacker who can access the relevant web interface may execute commands with the privileges of the router service.
A critical command-injection vulnerability in the Linksys E1700's setLinksysIpv6 function allows crafted IPv6 6rd configuration values to influence operating-system command execution.
Because the affected /goform/setLinksysIpv6 endpoint can be reached remotely, an attacker who can access the relevant web interface may execute commands with the privileges of the router service.
Affected context
The vulnerability occurs in Linksys E1700 firmware version 1.0.0.4.003 when the /goform/setLinksysIpv6 handler processes the _6rd_prefix or _6rd_prefix_len parameters. Risk depends on whether the endpoint is remotely reachable and whether supplied values are incorporated into operating-system commands without strict validation or safe argument handling.
The vulnerability occurs in Linksys E1700 firmware version 1.0.0.4.003 when the /goform/setLinksysIpv6 handler processes the _6rd_prefix or _6rd_prefix_len parameters. Risk depends on whether the endpoint is remotely reachable and whether supplied values are incorporated into operating-system commands without strict validation or safe argument handling.
Exploit preconditions
- Attack surface: The router's HTTP form endpoint at
/goform/setLinksysIpv6 - Required access: Network reachability to the management interface; authentication requirements depend on the device's access-control configuration
- Trigger point: Processing of the
_6rd_prefixor_6rd_prefix_lenparameters - Why exploitation is possible: User-controlled values reach command execution logic without sufficient separation between data and shell instructions
- Attack surface: The router's HTTP form endpoint at
/goform/setLinksysIpv6 - Required access: Network reachability to the management interface; authentication requirements depend on the device's access-control configuration
- Trigger point: Processing of the
_6rd_prefixor_6rd_prefix_lenparameters - Why exploitation is possible: User-controlled values reach command execution logic without sufficient separation between data and shell instructions
Why this happens
The underlying bug is an OS command-injection flaw caused by incorporating externally controlled parameter values into operating-system command processing. When input is concatenated into a shell command or passed through an unsafe command interpreter without strict allowlisting and argument separation, command syntax may be interpreted as executable logic. This maps primarily to CWE-78: Improper Neutralization of Special Elements used in an OS Command, with CWE-77: Improper Neutralization of Special Elements in Output Used by a Downstream Component also relevant to the broader command-injection pattern.
The underlying bug is an OS command-injection flaw caused by incorporating externally controlled parameter values into operating-system command processing. When input is concatenated into a shell command or passed through an unsafe command interpreter without strict allowlisting and argument separation, command syntax may be interpreted as executable logic. This maps primarily to CWE-78: Improper Neutralization of Special Elements used in an OS Command, with CWE-77: Improper Neutralization of Special Elements in Output Used by a Downstream Component also relevant to the broader command-injection pattern.
Potential impact
- An attacker may execute arbitrary commands on the router
- The device could be taken over or rendered unavailable
- Network traffic, credentials, or configuration data could be exposed
- The router may be used to access other systems on the local network
- Malicious changes could persist in device settings or startup behavior
- An attacker may execute arbitrary commands on the router
- The device could be taken over or rendered unavailable
- Network traffic, credentials, or configuration data could be exposed
- The router may be used to access other systems on the local network
- Malicious changes could persist in device settings or startup behavior
General mitigation guidance
Mitigation generally focuses on preventing user-controlled input from becoming shell syntax and reducing the privileges available to management services.
Common defensive patterns include:
- Avoiding shell invocation when a direct process or library API is available
- Passing command arguments through structured interfaces rather than string concatenation
- Applying strict allowlists and type-aware validation to IPv6 configuration fields
- Rejecting unexpected characters, formats, ranges, and encodings before processing
- Restricting management interfaces to trusted networks and using strong access controls
- Running web-management components with the minimum privileges required
- Applying network segmentation and read-only or integrity-protected configuration controls where practical
Mitigation generally focuses on preventing user-controlled input from becoming shell syntax and reducing the privileges available to management services.
Common defensive patterns include:
- Avoiding shell invocation when a direct process or library API is available
- Passing command arguments through structured interfaces rather than string concatenation
- Applying strict allowlists and type-aware validation to IPv6 configuration fields
- Rejecting unexpected characters, formats, ranges, and encodings before processing
- Restricting management interfaces to trusted networks and using strong access controls
- Running web-management components with the minimum privileges required
- Applying network segmentation and read-only or integrity-protected configuration controls where practical
How teams detect issues like this
Organizations can look for command-injection risks through:
- Static analysis rules identifying shell execution APIs and string-built commands
- Code review checks for request parameters flowing into process, shell, or system calls
- Tests using boundary values and malformed input to verify strict validation behavior
- Runtime monitoring for unexpected child processes launched by router management services
- Web and network logs showing unusual requests to configuration endpoints
- Policy enforcement that requires parameterized process execution and approved input validators
Automated security review tools may help identify data flows from HTTP parameters into command-execution functions.
Organizations can look for command-injection risks through:
- Static analysis rules identifying shell execution APIs and string-built commands
- Code review checks for request parameters flowing into process, shell, or system calls
- Tests using boundary values and malformed input to verify strict validation behavior
- Runtime monitoring for unexpected child processes launched by router management services
- Web and network logs showing unusual requests to configuration endpoints
- Policy enforcement that requires parameterized process execution and approved input validators
Automated security review tools may help identify data flows from HTTP parameters into command-execution functions.
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| linksys. | linksys.com/ |
