GO-2026-5026

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Source
https://pkg.go.dev/vuln/GO-2026-5026
Import Source
https://vuln.go.dev/ID/GO-2026-5026.json
JSON Data
https://api.osv.dev/v1/vulns/GO-2026-5026
Aliases
Downstream
Related
Published
2026-05-22T02:46:43Z
Modified
2026-08-19T10:45:05.842303854Z
Summary
Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna
Details

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode("xn--example-.com") incorrectly returns the name "example.com" rather than an error.

This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject "example.com" but permit "xn--example-.com". If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name "example.com".

Database specific 
{
    "review_status": "REVIEWED",
    "url": "https://pkg.go.dev/vuln/GO-2026-5026"
}
References
Credits
    • KC1zs4 (https://github.com/KC1zs4)

Affected packages

Go / stdlib

Package

Name
stdlib
View open source insights on deps.dev
Purl
pkg:golang/stdlib

Affected ranges

Type
SEMVER
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.25.13
Introduced
1.26.0-0
Fixed
1.26.6
Introduced
1.27.0-0
Fixed
1.27.0-rc.3

Ecosystem specific 

{
    "imports": [
        {
            "path": "net/http",
            "symbols": [
                "Client.CloseIdleConnections",
                "Client.Do",
                "Client.Get",
                "Client.Head",
                "Client.Post",
                "Client.PostForm",
                "ClientConn.Close",
                "ClientConn.RoundTrip",
                "Get",
                "Head",
                "Post",
                "PostForm",
                "Transport.CloseIdleConnections",
                "Transport.NewClientConn",
                "Transport.RoundTrip",
                "http1ClientConn.Close",
                "http1ClientConn.RoundTrip",
                "http2ClientConn.RoundTrip",
                "http2RoundTripper.RoundTrip",
                "idnaASCII"
            ]
        },
        {
            "path": "net/http/internal/http2",
            "symbols": [
                "Transport.AddConn",
                "Transport.RoundTrip",
                "Transport.RoundTripOpt",
                "authorityAddr"
            ]
        }
    ]
}

Database specific

source 
"https://vuln.go.dev/ID/GO-2026-5026.json"

Go / golang.org/x/net

Package

Name
golang.org/x/net
View open source insights on deps.dev
Purl
pkg:golang/golang.org/x/net

Affected ranges

Type
SEMVER
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
0.55.0

Ecosystem specific 

{
    "imports": [
        {
            "path": "golang.org/x/net/idna",
            "symbols": [
                "Profile.ToASCII",
                "Profile.ToUnicode",
                "Profile.process",
                "ToASCII",
                "ToUnicode"
            ]
        }
    ]
}

Database specific

source 
"https://vuln.go.dev/ID/GO-2026-5026.json"