CVE-2026-54637 Dragonfly scheduler v1 gRPC unauthenticated SSRF via attacker-controlled PeerHost in DownloadTinyFile
Remote attackers can exploit unauthenticated gRPC endpoints to perform Server-Side Request Forgery, probing internal services and retrieving limited response data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54637?
CVE-2026-54637 is a medium-severity server-side request forgery vulnerability in dragonflyoss dragonfly, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Dragonfly is an open source P2P-based file distribution and image acceleration system. Prior to 2.4.4-rc.3, the scheduler's default unauthenticated v1 gRPC flow accepts attacker-controlled PeerHost.Ip and PeerHost.DownPort values through RegisterPeerTask and ReportPeerResult, storeHost copies those values into resource.Host, and handlePeerSuccess invokes Peer.DownloadTinyFile() for a TINY task. DownloadTinyFile() in scheduler/resource/standard/peer.go builds an HTTP GET request from the supplied address without destination validation, allowing a remote attacker to probe loopback, link-local, and private services and place up to TinyFileSize, 128 bytes, of a response in Task.DirectPiece for later retrieval. PeerHost.DownPort is restricted to ports 1024 through 65534, and the issue provides read SSRF rather than remote code execution. The remediation blocks loopback and link-local targets, while RFC1918 destinations remain reachable because IsGlobalUnicast accepts private ranges. This issue is fixed in 2.4.4-rc.3.
Weakness: CWE-918
Which versions are affected by CVE-2026-54637?
3 open source packages ship an affected version, including d7y.io/dragonfly/v2.
| Package | Affected | Fixed in |
|---|---|---|
d7y.io/dragonfly/v2 Go | All versions | 2.4.4-rc.3 |
d7y.io/dragonfly/v2 Go | All versions | 2.4.4-rc.3 |
d7y.io/dragonfly/v2 Go | All versions | 2.4.4-rc.3 |
How do I fix CVE-2026-54637?
Upgrade d7y.io/dragonfly/v2 to 2.4.4-rc.3 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-54637 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54637 exists.
Sources
Also known as CVE-2026-54709, GHSA-chwm-m7g7-685g, GO-2026-5910.