Cloudreve: SSRF guard bypass: checkIP does not decode IPv6-transition wrappers (NAT64, IPv4-compatible, 6to4) reaching internal and cloud-metadata addresses (CVE-2026-79913) | HOL Guard CVE

Medium · CVSS 6.5CVE-2026-79913

Cloudreve: SSRF guard bypass: checkIP does not decode IPv6-transition wrappers (NAT64, IPv4-compatible, 6to4) reaching internal and cloud-metadata addresses

Answer in brief

CVE-2026-79913 records a Medium severity (CVSS 6.5) vulnerability in Cloudreve: SSRF guard bypass: checkIP does not decode IPv6-transition wrappers (NAT64, IPv4-compatible, 6to4) reaching internal and cloud-metadata addresses. The current sources do not mark it as known exploited. The current feed maps cloudreve/cloudreve (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 22, 2026Updated Sep 22, 2026Source checked Sep 22, 2026First seen by HOL Sep 22, 2026Material review Sep 22, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps cloudreve/cloudreve (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
cloudreve/cloudrevegeneric	<4.18.0	4.18.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for cloudreve/cloudreve.
Review the reported fix. Update cloudreve/cloudreve to 4.18.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 22, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.