net-http-httputil up to 1.25.9/1.26.2 on Go Query Parameter Rewrite request smuggling

Summaryinfo

A vulnerability, which was classified as problematic, has been found in net-http-httputil up to 1.25.9/1.26.2 on Go. Affected is the function Rewrite of the component Query Parameter Handler. The manipulation leads to request smuggling. This vulnerability is listed as CVE-2026-39825. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in net-http-httputil up to 1.25.9/1.26.2 on Go. It has been rated as problematic. This issue affects the function Rewrite of the component Query Parameter Handler. The manipulation with an unknown input leads to a request smuggling vulnerability. Using CWE to declare the problem leads to CWE-444. The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. Impacted is integrity. The summary by CVE is:

ReverseProxy can forward queries containing parameters not visible to Rewrite functions. When used with a Rewrite function, or a Director function which parses query parameters, ReverseProxy sanitizes the forwarded request to remove query parameters which are not parsed by url.ParseQuery. ReverseProxy does not take ParseQuery's limit on the total number of query parameters (controlled by GODEBUG=urlmaxqueryparams=N) into account. This can permit ReverseProxy to forward a request containing a query parameter that is not visible to the Rewrite function. For example, the query "a1=x&a2=x&...&a10000=x&hidden=y" can forward the parameter "hidden=y" while hiding it from the proxy's Rewrite function.

The identification of this vulnerability is CVE-2026-39825 since 04/07/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 315061 (SUSE SLED15 / SLES15 Security Update : go1.25 (SUSE-SU-2026:1862-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.25.10 or 1.26.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202605-1456), Tenable (315061), EUVD (EUVD-2026-28425) and CERT Bund (WID-SEC-2026-1437). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Splunk Splunk Enterprise
• Red Hat Enterprise Linux
• Google Container-Optimized OS
• Amazon Linux 2
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Microsoft Azure Linux
• Golang Go
• Red Hat OpenShift

Productinfo

Name

• net-http-httputil

Version

• 1.25.0
• 1.25.1
• 1.25.2
• 1.25.3
• 1.25.4
• 1.25.5
• 1.25.6
• 1.25.7
• 1.25.8
• 1.25.9
• 1.26.0
• 1.26.1
• 1.26.2

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion