How severe is CVE-2026-39825?

CVE-2026-39825 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-39825 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39825?

CVE-2026-39825 affects Golang Go. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-39825?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-39825 have an EU (EUVD) identifier?

Yes. CVE-2026-39825 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28425.

When was CVE-2026-39825 published?

CVE-2026-39825 was published on 2026-05-07 and last updated on 2026-06-17.

CVE-2026-39825

CVE-2026-39825 is a medium-severity vulnerability in Golang Go with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-28425
Affected product: Golang Go
Published: 2026-05-07
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-39825?: 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.
How severe is CVE-2026-39825?: CVE-2026-39825 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-39825 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39825?: CVE-2026-39825 affects Golang Go. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-39825?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-39825 have an EU (EUVD) identifier?: Yes. CVE-2026-39825 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28425.
When was CVE-2026-39825 published?: CVE-2026-39825 was published on 2026-05-07 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*

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