Home/CVE/ReverseProxy can forward queries containing parameters not visible to Rewrite functions. When used with a Rewrite functi
CVE

CVE-2026-39825

ReverseProxy can forward queries containing parameters not visible to Rewrite functions. When used with a Rewrite functi

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.

MEDIUM · CVSS 5.3 EPSS 0.00012
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
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Affected Products & Versions

2
golang go< 1.25.10
golang go>= 1.26.0 and < 1.26.3
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Go stdlib fixed in 1.25.10, 1.26.3
▣

Scoring & Timeline

5.3
MEDIUM · CVSS v3.1 · security@golang.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD07 May 2026 · 08:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

7
suse-csafopenSUSE-SU-2026:20763-1
suse-csafopenSUSE-SU-2026:20762-1
suse-csafSUSE-SU-2026:1861-1
suse-csafSUSE-SU-2026:1862-1
msrcCVE-2026-39825
🔗

References & Sources

4
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://go.dev/cl/770541Patch
https://go.dev/issue/78948Issue Tracking
https://groups.google.com/g/golang-announce/c/qcCIEXso47MRelease Notes
https://pkg.go.dev/vuln/GO-2026-4976Vendor Advisory
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