CVE-2026-9639 | Authenticated Denial of Service via Malicious Backup Tarball in LXD

Exp

Nil-pointer dereference in CreateCustomVolumeFromBackup in LXD up to version 6.8 and 5.21 on Linux allows an authenticated user with can_create_storage_volumes permissions to cause a denial of service via a specially crafted custom-volume backup tarball that omits the expires_at snapshot field.

Published: 2026-06-26 Last update: 2026-07-02 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-9639 is rated Exploit Available (51.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.38%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-9639

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-9639

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-27 — 0.38% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-9639

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-9639

OS Trackers for CVE-2026-9639

vendor priority summary link
debian end-of-life CVE-2026-9639 end-of-life priority: Debian including 1 source packages (lxd), 2 status rows across 2 suites (bookworm, trixie): open 1, resolved 1. https://security-tracker.debian.org/tracker/CVE-2026-9639
ubuntu medium CVE-2026-9639 medium priority: Ubuntu including 1 source packages (lxd), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): DNE 4, not-affected 3, needs-triage 1. https://ubuntu.com/security/CVE-2026-9639

Affected software / configurations for CVE-2026-9639

Vendor Product Version Raw CPE
canonical lxd >= 5.0.0, < 5.21.5 cpe:2.3:a:canonical:lxd:*:*:*:*:*:*:*:*
canonical lxd >= 6.0, < 6.9 cpe:2.3:a:canonical:lxd:*:*:*:*:*:*:*:*

References for CVE-2026-9639

cvelogic Threat Intelligence