CVE-2026-87799: CWE-59 Improper link resolution before file access ('link following') in Canonical LXD
Improper link resolution in the migration receive path in Canonical LXD versions 4.0 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client that can create instances or custom storage volumes in a project, or a malicious migration source server, to write attacker-controlled files to arbitrary paths on the target host as root, leading to full host compromise. The attacker does this with a crafted rsync or btrfs send stream that plants a symlink in the transferred volume, such as rootfs or root.img, and then writes through it.
AI Analysis
Technical Summary
The vulnerability CVE-2026-87799 in Canonical LXD is due to improper link resolution (CWE-59) in the migration receive path. Authenticated clients able to create instances or custom storage volumes, or malicious migration source servers, can exploit this by sending a crafted rsync or btrfs send stream that includes a symlink in the transferred volume (e.g., rootfs or root.img). This symlink allows writing attacker-controlled files to arbitrary paths on the target host with root privileges, resulting in full host compromise. The flaw affects LXD versions >=4.0.0 <4.0.14, >=5.0.0 <5.0.10, >=5.21.0 <5.21.8, and >=6.0 <6.10. Fixes are available in versions 4.0.14, 5.0.10, 5.21.8, and 6.10.
Potential Impact
Successful exploitation allows an attacker with authenticated access and certain privileges, or a malicious migration source server, to write arbitrary files as root on the host system. This leads to full host compromise, including complete control over the host environment. The vulnerability has a critical severity with a CVSS score of 9.9, indicating high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
A fix is available and has been released in Canonical LXD versions 4.0.14, 5.0.10, 5.21.8, and 6.10. Users should upgrade to these or later versions to remediate this vulnerability. No additional mitigation steps are indicated beyond applying the official patches.
CVE-2026-87799: CWE-59 Improper link resolution before file access ('link following') in Canonical LXD
Description
Improper link resolution in the migration receive path in Canonical LXD versions 4.0 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client that can create instances or custom storage volumes in a project, or a malicious migration source server, to write attacker-controlled files to arbitrary paths on the target host as root, leading to full host compromise. The attacker does this with a crafted rsync or btrfs send stream that plants a symlink in the transferred volume, such as rootfs or root.img, and then writes through it.
CVSS v3.1
Score 9.9critical
Affected software
Canonical
LXD
pkg:github/LXDRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-87799 in Canonical LXD is due to improper link resolution (CWE-59) in the migration receive path. Authenticated clients able to create instances or custom storage volumes, or malicious migration source servers, can exploit this by sending a crafted rsync or btrfs send stream that includes a symlink in the transferred volume (e.g., rootfs or root.img). This symlink allows writing attacker-controlled files to arbitrary paths on the target host with root privileges, resulting in full host compromise. The flaw affects LXD versions >=4.0.0 <4.0.14, >=5.0.0 <5.0.10, >=5.21.0 <5.21.8, and >=6.0 <6.10. Fixes are available in versions 4.0.14, 5.0.10, 5.21.8, and 6.10.
Potential Impact
Successful exploitation allows an attacker with authenticated access and certain privileges, or a malicious migration source server, to write arbitrary files as root on the host system. This leads to full host compromise, including complete control over the host environment. The vulnerability has a critical severity with a CVSS score of 9.9, indicating high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
A fix is available and has been released in Canonical LXD versions 4.0.14, 5.0.10, 5.21.8, and 6.10. Users should upgrade to these or later versions to remediate this vulnerability. No additional mitigation steps are indicated beyond applying the official patches.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- canonical
- Date Reserved
- 2026-09-09T10:00:46.383Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aba6ca0f7a7c54106b9890c
Added to database: 09/28/2026, 13:33:20 UTC
Last enriched: 09/28/2026, 13:47:54 UTC
Last updated: 09/29/2026, 01:57:22 UTC
Views: 15
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.