Security Digest · Vulnerability record
CVE-2026-48750: Incus has an arbitrary file write on host via `exec-output` symlink in crafted image
Incus is a system container and virtual machine manager.
CVSS 9.9 Critical EPSS 0.7% · p54
Should you act?
Critical, preconditions apply
Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.7%, percentile 54: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 54% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
github.com/lxc/incus/v7/cmd/incusd(Go) < 7.2.0, fixed in 7.2.0. Check your lockfile, including transitive dependencies.
What it is
Incus is a system container and virtual machine manager. Prior to version 7.2.0, the record-output parameter of the /instances/$name/exec endpoint stores the output of the command in the exec-output directory of the instance. If exec-output is a symlink, file named execUUID.stdout and execUUID.stderr can be written to an arbitrary location where the .stdout file will contain arbitrary content. This behavior can be abused for arbitrary command execution. Version 7.2.0 contains a patch.
From the GitHub advisory
Summary
The record-output parameter of the /instances/$name/exec endpoint stores the output of the command in the exec-output directory of the instance. If exec-output is a symlink, file named execUUID.stdout and execUUID.stderr can be written to an arbitrary location where the .stdout file will contain arbitrary content. This behavior can be abused for arbitrary command execution.
Details
When an image is unpacked, top-level symlinks are extracted as is; allowing for exec-output to be placed on disk. In instanceexec.go, os.Mkdir continues of exec-output exists and os.OpenFile follows the exec-output symlink.
PoC
Weakness type: CWE-73.
Product: github.com/lxc/incus/v7/cmd/incusd (Go) · Assigned by: GitHub_M · Published: 2026-08-21
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Go | github.com/lxc/incus/v7/cmd/incusd | < 7.2.0 | 7.2.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| lxc | incus | < 7.2.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.9 Critical | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
| GitHub | 3.1 | 9.9 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: low (any account)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.73% probability of exploitation activity in the next 30 days; percentile 54.
Timeline
- — GitHub-reviewed advisory GHSA-73hr-m85f-64v9 published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-73hr-m85f-64v9 github.com
- CVE.org record CVE-2026-48750 cve.org
- NVD entry CVE-2026-48750 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com