Linksys WRT54GL 4.30.18 Traceroute Diagnostic Function apply.cgi system traceroute_ip os command injection

Summaryinfo

A vulnerability marked as very critical has been reported in Linksys WRT54GL 4.30.18. This affects the function system of the file apply.cgi of the component Traceroute Diagnostic Function. Performing a manipulation of the argument traceroute_ip results in os command injection. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability was named CVE-2026-121931. The attack may be initiated remotely. In addition, an exploit is available. The vendor was contacted early about this disclosure but did not respond in any way.

Detailsinfo

A vulnerability was found in Linksys WRT54GL 4.30.18. It has been classified as very critical. This affects the function system of the file apply.cgi of the component Traceroute Diagnostic Function. The manipulation of the argument traceroute_ip with an unknown input leads to a os command injection vulnerability. CWE is classifying the issue as CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-121931. The exploitability is told to be easy. It is possible to initiate the attack remotely. Additional levels of successful authentication are necessary for exploitation. Technical details and a public exploit are known. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/04/2026). The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

The exploit is shared for download at github.com. It is declared as proof-of-concept. The vendor was contacted early about this disclosure but did not respond in any way.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Router Operating System

Vendor

• Linksys

Name

• WRT54GL

Version

• 4.30.18

License

• commercial

Support

• end of life

Website

• Vendor: https://www.linksys.com/

CPE 2.3info

• 🔒

CPE 2.2info

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Accepted

• Submit #1024099: Linksys WRT54GL 4.30.18 OS Command Injection (CWE-78) (by liuyingqi)

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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