Account users in Apache CloudStack by default are allowed to upload and register templates for deploying instances and volumes for attaching them as data disks to their existing instances. Due to missing validation checks for KVM-compatible templates or volumes in CloudStack 4.0.0 through 4.18.2.3 and 4.19.0.0 through 4.19.1.1, an attacker that can upload or register templates and volumes, can use them to deploy malicious instances or attach uploaded volumes to their existing instances on KVM-based environments and exploit this to gain access to the host filesystems that could result in the compromise of resource integrity and confidentiality, data loss, denial of service, and availability of KVM-based infrastructure managed by CloudStack.
Users are recommended to upgrade to Apache CloudStack 4.18.2.4 or 4.19.1.2, or later, which addresses this issue.
Additionally, all user-uploaded or registered KVM-compatible templates and volumes can be scanned and checked that they are flat files that should not be using any additional or unnecessary features. For example, operators can run this on their secondary storage(s) and inspect output. An empty output for the disk being validated means it has no references to the host filesystems; on the other hand, if the output for the disk being validated is not empty, it might indicate a compromised disk.
for file in $(find /path/to/storage/ -type f -regex [a-f0-9\-]*.*); do echo "Retrieving file [$file] info. If the output is not empty, that might indicate a compromised disk; check it carefully."; qemu-img info -U $file | grep file: ; printf "\n\n"; done
The command can also be run for the file-based primary storages; however, bear in mind that (i) volumes created from templates will have references for the templates at first and (ii) volumes can be consolidated while migrating, losing their references to the templates. Therefore, the command execution for the primary storages can show both false positives and false negatives.
For checking the whole template/volume features of each disk, operators can run the following command:
for file in $(find /path/to/storage/ -type f -regex [a-f0-9\-]*.*); do echo "Retrieving file [$file] info."; qemu-img info -U $file; printf "\n\n"; done
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.5): severity, escalated by confirmed exploitation. This CVE's 8.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 1.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
The CVE record names the fixed release. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it