CVE-2026-79913 Cloudreve: SSRF guard bypass: checkIP does not decode IPv6-transition wrappers (NAT64, IPv4-compatible, 6to4) reaching internal and cloud-metadata addresses
Authenticated users can bypass SSRF protections using IPv6 transition wrappers to access internal services and cloud metadata credentials.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-79913?
CVE-2026-79913 is a medium-severity server-side request forgery vulnerability in cloudreve, published on 22 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Cloudreve is a self-hosted file management and sharing system. Prior to 4.18.0, the ValidateExternalURL server-side request forgery guard in pkg/request/ssrf.go passes resolved addresses to checkIP without decoding NAT64, IPv4-compatible, and 6to4 IPv4-in-IPv6 transition forms. An authenticated user with remote-download access can provide SrcUri through RemoteDownloadTask.createDownloadTask so a wrapper embedding a loopback, private, link-local, or cloud metadata IPv4 address is classified as public and fetched, exposing internal service responses and cloud instance credentials. IPv4-mapped IPv6 addresses remain blocked because Go converts that form with net.IP.To4. This issue is fixed in version 4.18.0.
Which versions are affected by CVE-2026-79913?
5 open source packages ship an affected version, including github.com/cloudreve/Cloudreve/v4, github.com/cloudreve/Cloudreve and github.com/cloudreve/Cloudreve/v3.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cloudreve/Cloudreve/v4 Go | All versions | 4.0.0-20260715072853-1c5cad6dec7e |
github.com/cloudreve/Cloudreve/v4 Go | All versions | 4.0.0-20260715072853-1c5cad6dec7e |
github.com/cloudreve/Cloudreve/v4 Go | All versions | 4.0.0-20260715072853-1c5cad6dec7e |
github.com/cloudreve/Cloudreve Go | All versions | None |
github.com/cloudreve/Cloudreve/v3 Go | All versions | None |
How do I fix CVE-2026-79913?
Upgrade github.com/cloudreve/Cloudreve/v4 to 4.0.0-20260715072853-1c5cad6dec7e or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-79913 being exploited?
There is no known exploitation of CVE-2026-79913 in the wild and no public exploit code.
Sources
Also known as GHSA-jvh5-97xg-v99f, GO-2026-6572.