x/vuln: false positive for GO-2025-3408

[ping-localhost]

govulncheck version

Go: go1.23.5
Scanner: [email protected]
DB: https://vuln.go.dev
DB updated: 2025-01-29 20:18:58 +0000 UTC

Does this issue reproduce at the latest version of golang.org/x/vuln?

Yes

Output of go env in your module/workspace:

GO111MODULE='on'
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/mitchell/Library/Caches/go-build'
GOENV='/Users/mitchell/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/mitchell/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/mitchell/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/homebrew/opt/go/libexec'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/opt/homebrew/opt/go/libexec/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.23.5'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/mitchell/Library/Application Support/go/telemetry'
GCCGO='gccgo'
GOARM64='v8.0'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/c6/4l4ylj_530z56dccw0b7_pq00000gn/T/go-build2006941850=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

Using github.com/mattermost/mattermost/server/public/model in my project, which has a dependency on github.com/hashicorp/yamux (which I don't use) causes [email protected] to imply that GO-2025-3408 affects me (via sync.Once which is called by time.LoadLocation).

Sample code

package main

import (
	"fmt"
	"time"

	"github.com/mattermost/mattermost/server/public/model"
)

func main() {
	// Use something that calls `sync.Once`
	netherlands, err := time.LoadLocation("Europe/Amsterdam")
	if err != nil {
		panic(err)
	}

	// Just use anything from the Mattermost package as an example
	post := &model.Post{Message: "Hello!", ChannelId: "ID"}

	// Output because we can
	fmt.Println(netherlands, post.Message)
}

Repository: https://github.com/ping-localhost/vuln-check-reproducible

What did you see happen?

[16:56:12] ➜  vuln-check-reproducible git:(master) govulncheck ./...                                  
=== Symbol Results ===

Vulnerability #1: GO-2025-3408
    DefaultConfig has dangerous defaults causing hung Read in
    github.com/hashicorp/yamux
  More info: https://pkg.go.dev/vuln/GO-2025-3408
  Module: github.com/hashicorp/yamux
    Found in: github.com/hashicorp/[email protected]
    Fixed in: N/A
    Example traces found:
      #1: main.go:12:39: vuln.main calls time.LoadLocation, which eventually calls yamux.Client
      #2: main.go:12:39: vuln.main calls time.LoadLocation, which eventually calls yamux.DefaultConfig

Your code is affected by 1 vulnerability from 1 module.
This scan found no other vulnerabilities in packages you import or modules you
require.
Use '-show verbose' for more details.

What did you expect to see?

Since I never actually use Yamux, I do not expect the CVE to be picked up. Somewhere along the line govulncheck thinks that sync.Once.Do will call yamux.

[zpavlinovic]

How is this a false negative? Perhaps you mean a false positive?

[ping-localhost]

How is this a false negative? Perhaps you mean a false positive?

You're totally correct. I properly named my repository and then messed up in the issue. 🤦‍♂️

My bad!

[gabyhelp]

Related Issues

• x/vuln: incorrect version is suggested as a fixed version for a vulnerability with multiple packages #54913 (closed)
• x/vuln/cmd/govulncheck: stack overflow #51560 (closed)
• x/vuln: json output always exits 0 #61704 (closed)
• x/vuln/cmd/govulncheck: unexpected trace with uncalled methods for GO-2024-3106 #69446 (closed)
• x/vuln: false negative for GO-2024-3321 #71449
• x/vuln: default govulncheck output is very long #71415
• x/vuln: govulncheck does not match when using vulnerable symbol #55937 (closed)
• x/vuln: Panics regularly #54995 (closed)
• x/vuln: Cannot handle multiple "fixed" events on vulns.json #55035 (closed)
• x/vuln: Panic "cannot range over: func(yield func(K, V) bool) using golang 1.23.0 #68978 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[zpavlinovic]

Since I never actually use Yamux, I do not expect the CVE to be picked up.

govulncheck does not check just the modules you directly use. It also analyzes transitive dependencies. This is absolutely necessary as such dependencies can also be vulnerable and if your code eventually exercises them, your code is also vulnerable.

Somewhere along the line govulncheck thinks that sync.Once.Do will call yamux.

It could be that your code indeed does not call yamux. It is hard for me to tell, but it looks that way. In general, govulncheck can have false positives (this is an inherent property of all vulnerability checking tools). We are working on providing suppression mechanisms for false positives.

[seankhliao]

I believe this is the same as #69446 (closed without resolution).
where govulncheck lacks context sensitvity #69446 (comment)

The trace is as below, which can't be right (the standard library won't call an external dependency).

Vulnerability #1: GO-2025-3408
    DefaultConfig has dangerous defaults causing hung Read in
    github.com/hashicorp/yamux
  More info: https://pkg.go.dev/vuln/GO-2025-3408
  Module: github.com/hashicorp/yamux
    Found in: github.com/hashicorp/[email protected]
    Fixed in: N/A
    Example traces found:
      #1: for function github.com/hashicorp/yamux.Client
        main @ github.com/ping-localhost/vuln-check-reproducible/main.go:12:39
        LoadLocation @ stdlib/src/time/zoneinfo.go:675:17
        Once.Do @ stdlib/src/sync/once.go:69:11
        Once.doSlow @ stdlib/src/sync/once.go:78:4
        getGRPCMuxer @ github.com/hashicorp/go-plugin/client.go:1153:48
        NewGRPCClientMuxer @ github.com/hashicorp/go-plugin/internal/grpcmux/grpc_client_muxer.go:53:27
        Client @ github.com/hashicorp/yamux/mux.go:105:6
      #2: for function github.com/hashicorp/yamux.DefaultConfig
        main @ github.com/ping-localhost/vuln-check-reproducible/main.go:12:39
        LoadLocation @ stdlib/src/time/zoneinfo.go:675:17
        Once.Do @ stdlib/src/sync/once.go:69:11
        Once.doSlow @ stdlib/src/sync/once.go:78:4
        getGRPCMuxer @ github.com/hashicorp/go-plugin/client.go:1153:48
        NewGRPCClientMuxer @ github.com/hashicorp/go-plugin/internal/grpcmux/grpc_client_muxer.go:48:28
        DefaultConfig @ github.com/hashicorp/yamux/mux.go:58:6

[ping-localhost]

@seankhliao thank you for posting the trace. It is exactly why I opened this issue, as that shouldn't happen.

[zpavlinovic]

@seankhliao thank you for posting the trace. It is exactly why I opened this issue, as that shouldn't happen.

We currently don't have immediate plans on improving the precision of govulncheck. (Due to the nature of the problem, this can in principle be done indefinitely). We are instead focusing on providing supression mechanisms.