CVE-2026-87799 Arbitrary file write on LXD host via symlink in migration stream
An authenticated attacker or malicious migration source can write arbitrary files to the host via symlink exploitation in LXD, leading to full host compromise.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-87799?
CVE-2026-87799 is a critical path traversal vulnerability in Canonical LXD, published on 28 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-59
Which versions are affected by CVE-2026-87799?
How do I fix CVE-2026-87799?
No fix has been published for CVE-2026-87799 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-87799 being exploited?
There is no known exploitation of CVE-2026-87799 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-87799, GHSA-fmc3-3cpq-6whr, UBUNTU-CVE-2026-87799.