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fix(auth): restrict oauth2 login avatar fetch to external hosts #38290

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fix(auth): restrict oauth2 login avatar fetch to external hosts #38290

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10e444d
restrict oauth2 avatar fetch to external hosts
insaf021 Jul 1, 2026
bf63bee
Merge branch 'main' into oauth2-avatar-ssrf
insaf021 Jul 4, 2026
fc83549
Merge branch 'main' into oauth2-avatar-ssrf
insaf021 Jul 5, 2026
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23 changes: 21 additions & 2 deletions routers/web/auth/oauth.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,15 +13,18 @@ import (
"net/url"
"sort"
"strings"
"sync"
"time"

"gitea.dev/models/auth"
user_model "gitea.dev/models/user"
auth_module "gitea.dev/modules/auth"
"gitea.dev/modules/container"
"gitea.dev/modules/hostmatcher"
"gitea.dev/modules/httplib"
"gitea.dev/modules/log"
"gitea.dev/modules/optional"
"gitea.dev/modules/proxy"
"gitea.dev/modules/session"
"gitea.dev/modules/setting"
source_service "gitea.dev/services/auth/source"
Expand Down Expand Up @@ -296,7 +299,23 @@ func showLinkingLogin(ctx *context.Context, authSourceID int64, gothUser goth.Us
ctx.Redirect(setting.AppSubURL + "/user/link_account")
}

var oauth2AvatarHTTPClient = &http.Client{Timeout: 30 * time.Second}
// avatarURL comes from the provider (goth User.AvatarURL / the OIDC "picture" claim), so
// the fetch must not be allowed to reach internal hosts. Guard egress the same way webhook
// and migration requests are guarded, allowing only external (public) hosts.
var oauth2AvatarHTTPClient = sync.OnceValue(func() *http.Client {
return &http.Client{
Timeout: 30 * time.Second,
Transport: &http.Transport{
Proxy: proxy.Proxy(),
DialContext: hostmatcher.NewDialContext(
"oauth2-avatar",
hostmatcher.ParseHostMatchList("", hostmatcher.MatchBuiltinExternal),
nil,
setting.Proxy.ProxyURLFixed,
),
},
}
})

func oauth2UpdateAvatarIfNeed(ctx *context.Context, avatarURL string, u *user_model.User) {
if !setting.OAuth2Client.UpdateAvatar || len(avatarURL) == 0 {
Expand All @@ -310,7 +329,7 @@ func oauth2UpdateAvatarIfNeed(ctx *context.Context, avatarURL string, u *user_mo
// Some hosts (e.g. Wikimedia) reject Go's default User-Agent.
req.Header.Set("User-Agent", "Gitea "+setting.AppVer)

resp, err := oauth2AvatarHTTPClient.Do(req)
resp, err := oauth2AvatarHTTPClient().Do(req)
if err != nil {
log.Warn("fetch %q failed: %v", avatarURL, err)
return
Expand Down
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