Kopia: Unauthenticated RCE via SSH ProxyCommand Injection when --insecure --without-password is used

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Summary

CVECVE-2026-45695
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-16 16:19:08 UTC
Updated2026-07-16 19:16:45 UTC
DescriptionKopia is a cross-platform backup tool for Windows, macOS, and Linux with fast incremental backups, client-side end-to-end encryption, compression, and data deduplication. Prior to 0.23.0, Kopia's HTTP server started with --without-password accepts unauthenticated requests to /api/v1/repo/exists and forwards attacker-supplied SFTP storage configuration to blob.NewStorage, where externalSSH: true and sshArguments containing -oProxyCommand=<cmd> can cause exec.CommandContext("ssh") to invoke the command through OpenSSH. This issue is fixed in version 0.23.0.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.003480000 probability, percentile 0.271070000 (date 2026-07-20)

Problem Types: CWE-78 | CWE-306 | CWE-78 CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') | CWE-306 CWE-306: Missing Authentication for Critical Function

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Kopia Kopia affected < 0.23.0 Not specified

References

ReferenceSourceLinkTags
github.com/kopia/kopia/security/advisories/GHSA-2q4c-3mrw-63c3 [email protected] github.com
github.com/kopia/kopia/releases/tag/v0.23.0 [email protected] github.com
github.com/kopia/kopia/pull/5354 [email protected] github.com
github.com/kopia/kopia/commit/c26c6a1b9734c5089217986ffa5cd19f8a6b8900 [email protected] github.com
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