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CVE-2026-79775: rclone Archive Backend SquashFS Parser Denial of Service

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-25 · updated 2026-09-10
• Weakness: CWE-129

Description

rclone versions >= v1.72.0 and <= v1.74.4 (fixed in v1.75.0) contain multiple denial-of-service vulnerabilities in the archive backend's SquashFS parser, which relies on the github.com/diskfs/go-diskfs dependency. The parser fails to validate attacker-controlled superblock and metadata values before use. An attacker who can place or modify a SquashFS image in storage exposed through an rclone :archive: remote can craft a malicious image that triggers an integer division-by-zero panic (zero block size), an out-of-bounds slice panic (out-of-range inode metadata offset), or a non-progress CPU loop (truncated metadata stream). Variants 1 and 2 terminate the rclone process and, via 'rclone serve sftp', can crash the entire SFTP server; variant 3 causes sustained CPU consumption. Parsing is lazy, so a victim or remote client must address or descend into the malicious archive object to trigger it.

Affected products

• rclone: from 1.72.0 through 1.74.4

References

• https://github.com/rclone/rclone/security/advisories/GHSA-6jcg-q3wp-x2f4
• https://www.vulncheck.com/advisories/rclone-archive-backend-squashfs-parser-denial-of-service
• https://github.com/rclone/rclone/security/advisories/GHSA-6jcg-q3wp-x2f4

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