Image Handling and qemu-img Security Vulnerabilities¶

This document provides a comprehensive analysis of disclosed CVEs related to image handling and qemu-img across major virtualization platforms: oVirt, Proxmox VE, and OpenStack, as well as general qemu-img vulnerabilities.

Executive Summary¶

Image handling represents a critical attack surface in virtualization platforms. The vulnerabilities documented here fall into several categories:

Arbitrary File Access - Exploiting image format features (backing files, external data files, VMDK descriptors) to read arbitrary files from servers
Denial of Service - Resource exhaustion through maliciously crafted images
Privilege Escalation - Bypassing authorization or escalating to root
Code Execution - Memory corruption leading to arbitrary code execution

Cross-Platform qemu-img Vulnerabilities¶

These vulnerabilities affect qemu-img directly and impact all platforms using it.

CVE-2024-4467 - qemu-img 'info' Command Vulnerability¶

Attribute	Value
CVE ID	CVE-2024-4467
CVSS Score	7.8 (High)
CWE	CWE-400: Uncontrolled Resource Consumption
Affected Versions	qemu < 7.2.12, < 8.2.5, < 9.0.1

Description: A flaw in qemu-img's 'info' command allows specially crafted image files containing json:{} values describing block devices to cause excessive memory/CPU consumption or unauthorized file read/write operations.

Impact: - Denial of Service through resource exhaustion - Unauthorized read/write to external files on the host - Affects oVirt, Proxmox, and OpenStack deployments

Mitigation: Update to qemu 7.2.12, 8.2.5, or 9.0.1+.

CVE-2014-0144 - Block Driver Input Validation Failure¶

Attribute	Value
CVE ID	CVE-2014-0144
Severity	High
Affected Versions	qemu < 2.0.0

Description: qemu block drivers for CLOOP, QCOW2 v2, and other formats are vulnerable to memory corruptions, integer/buffer overflows due to missing input validations.

Impact: Remote code execution on host with qemu process privileges.

CVE-2014-0222 & CVE-2014-0223 - QCOW1 Integer Overflows¶

Attribute	Value
CVE IDs	CVE-2014-0222, CVE-2014-0223
CVSS Score	7.5 (High)
Affected Versions	qemu < 1.7.2

Description: Integer overflow flaws in QCOW version 1 handling allow memory corruption and potential code execution.

CVE-2008-2004 - RAW Image Format Probe Vulnerability¶

Attribute	Value
CVE ID	CVE-2008-2004
Severity	Moderate

Description: When image format is not explicitly specified, qemu probes the image header to guess format. A malicious guest can write a crafted header to trick qemu into using a different format, enabling arbitrary file access.

Key Lesson: Always explicitly specify image format with --format flag.

OpenStack Vulnerabilities¶

CVE-2024-32498 (OSSA-2024-001) - QCOW2 External Data File Access¶

Attribute	Value
CVE ID	CVE-2024-32498
CVSS Score	8.8 (High)
Affected Services	Cinder, Glance, Nova
Published	July 2024

Affected Versions: - Cinder: <22.1.3, >=23.0.0 <23.1.1, ==24.0.0 - Glance: <26.0.1, ==27.0.0, >=28.0.0 <28.0.2 - Nova: <27.3.1, >=28.0.0 <28.1.1, >=29.0.0 <29.0.3

Description: QCOW2 images have two mechanisms to read external files: backing files (fixed in 2015) and external data files (newly discovered). Attackers can craft images referencing sensitive files on the target server.

Impact: Unauthorized read access to /etc/passwd, configuration files, private keys, etc.

CVE-2024-40767 (OSSA-2024-002) - Incomplete Fix Regression¶

Attribute	Value
CVE ID	CVE-2024-40767
Affected Services	Nova
Published	July 2024

Description: Incomplete fix for CVE-2024-32498 and regression of CVE-2022-47951. Raw format images that are actually QCOW2/VMDK with backing file references can bypass protections.

Warning: These fixes cannot block malicious images already in Nova's cache.

CVE-2022-47951 (OSSA-2023-002) - VMDK Flat Descriptor File Access¶

Attribute	Value
CVE ID	CVE-2022-47951
CVSS Score	5.7 (Medium)
Affected Services	Cinder, Glance, Nova
Published	January 2023

Description: VMDK flat images can reference backing files through descriptor files, enabling unauthorized file access.

Impact: All Cinder and Nova deployments affected; Glance only if image conversion is enabled.

CVE-2024-44082 (OSSA-2024-003) - Ironic Image Processing¶

Attribute	Value
CVE ID	CVE-2024-44082
CVSS Score	4.3 (Medium)
Affected Services	Ironic, Ironic-Python-Agent
Published	September 2024

Description: Running qemu-img on untrusted images without format pre-specification allows exploitation of unsafe format features.

New Configuration Options: - conductor_always_validates_images = True - permitted_image_formats = raw,qcow2

CVE-2015-5162 (OSSA-2016-012) - Resource Exhaustion DoS¶

Attribute	Value
CVE ID	CVE-2015-5162
CVSS Score	5.5 (Medium)
Affected Services	Cinder, Glance, Nova

Description: Maliciously crafted disk images cause excessive RAM and CPU consumption. Fix ensures qemu-img runs with resource limits (2s CPU, 1GB RAM).

CVE-2015-1851 - Cinder Format Guessing Exploit¶

Attribute	Value
CVE ID	CVE-2015-1851
Affected Services	Cinder

Description: Cinder didn't specify input format to qemu-img convert. Attackers could create volumes with QCOW2 signatures containing base file references, causing Cinder (running as root) to embed arbitrary file contents.

Exploitation: 1. Create volume and attach to VM 2. Write QCOW2 signature with base-file reference from within VM 3. Trigger upload with cinder upload-to-image --disk-type qcow2 4. Uploaded image contains contents of referenced files

oVirt Vulnerabilities¶

CVE-2018-10908 - VDSM qemu-img Resource Exhaustion¶

Attribute	Value
CVE ID	CVE-2018-10908
CVSS Score	6.3-6.5 (Medium)
Affected Versions	VDSM < 4.20.37

Description: VDSM invokes qemu-img on untrusted inputs without resource limits. Specially crafted images cause unbounded memory/CPU consumption.

Mitigation: Upgrade VDSM to 4.20.37+.

CVE-2019-3831 - VDSM Privilege Escalation¶

Attribute	Value
CVE ID	CVE-2019-3831
CVSS Score	6.4-9.0 (Medium-High)
Affected Versions	VDSM 4.19 - 4.30.8

Description: The systemd_run function exposed to vdsm user can be abused to execute arbitrary commands as root.

CVE-2019-3879 - oVirt REST API Authorization Bypass¶

Attribute	Value
CVE ID	CVE-2019-3879
CVSS Score	6.5-8.1 (Medium-High)
Affected Versions	oVirt < 4.3.2.1

Description: RemoveDiskCommand is triggered as internal command, skipping permission validation. Users with Basic Operations role can delete disks.

CVE-2015-3456 (VENOM) - qemu FDC Buffer Overflow¶

Attribute	Value
CVE ID	CVE-2015-3456
Severity	Important

Description: Buffer overflow in qemu's Floppy Disk Controller emulation allows guest-to-host escape. Exploitable even without explicit floppy configuration.

Proxmox VE Vulnerabilities¶

CVE-2024-21545 - API Arbitrary File Read¶

Attribute	Value
CVE ID	CVE-2024-21545
CVSS Score	8.2 (High)
Affected Versions	Proxmox VE <= 8.2.2

Description: Insufficient safeguards against malicious API response values allow authenticated attackers with 'Sys.Audit' or 'VM.Monitor' privileges to download arbitrary host files including /etc/shadow and authentication keys.

Impact: Session token forgery and complete system takeover.

CVE-2022-35508 - SSRF and File Disclosure¶

Attribute	Value
CVE ID	CVE-2022-35508
CVSS Score	9.8 (Critical)
Affected Products	Proxmox VE, Proxmox Mail Gateway

Description: SSRF vulnerability when proxying HTTP requests between pve(pmg)proxy and pve(pmg)daemon. Unprivileged accounts can achieve SSRF and file disclosure.

Verification:

pveversion -v | grep libpve-http-server-perl

CVE-2023-43320 - Two-Factor Authentication Bypass¶

Attribute	Value
CVE ID	CVE-2023-43320
Severity	High
Affected Versions	PVE 5.4-8.0, PBS 1.1-3.0, PMG 7.1-8.0

Description: Privilege escalation by bypassing 2FA component.

Mitigation: Upgrade to Proxmox VE 8.1+.

CVE-2024-9486 - Kubernetes Image Builder Default Credentials¶

Attribute	Value
CVE ID	CVE-2024-9486
CVSS Score	9.8 (Critical)
Affected Product	Kubernetes Image Builder (Proxmox provider)

Description: VM images built with Kubernetes Image Builder retain default credentials from the build process.

Mitigation:

usermod -L builder

Image Format Specific Issues¶

QCOW/QCOW2 Encryption Weakness¶

The native AES encryption in QCOW/QCOW2 has design flaws: - AES-CBC with predictable IVs based on sector number - Vulnerable to chosen plaintext attacks - Passphrase directly used as encryption key - No key rotation capability

Recommendation: Use LUKS encryption instead.

Recurring Vulnerability Patterns¶

Pattern	Examples
Format auto-detection abuse	CVE-2008-2004, CVE-2015-1851, CVE-2024-44082
Backing file exploitation	CVE-2015-5163, CVE-2024-32498, CVE-2024-40767
VMDK descriptor exploitation	CVE-2022-47951, CVE-2024-40767
External data file exploitation	CVE-2024-32498
Resource exhaustion	CVE-2015-5162, CVE-2018-10908, CVE-2024-4467

Root Cause: RAW as Fallback Format¶

A fundamental design decision in qemu-img enables many of these vulnerabilities: any file that doesn't match a known format is treated as a valid "raw" disk image.

This means when qemu-img follows a backing file reference to /etc/shadow:

It opens the file and attempts format detection
/etc/shadow has no QCOW2/VMDK/VHD magic number
qemu-img treats it as a "raw" disk image (the fallback)
The file contents are read as disk data

If qemu-img instead rejected files without recognized disk image headers, these attacks would fail. A /etc/shadow file would be rejected as "not a valid disk image" rather than being silently accepted as "raw."

A more defensive design would require: - Known format magic numbers (QCOW2, VMDK, VHD, etc.), OR - Valid partition table (MBR/GPT) for raw images

This is why oslo.utils format_inspector detects MBR/GPT partition tables - to distinguish genuine raw disk images from arbitrary files that qemu-img would happily accept. See quirks.md for details.

Recommendations¶

For All Platforms¶

Always specify image format explicitly

qemu-img info --format=qcow2 image.qcow2
qemu-img convert -f qcow2 -O raw input.qcow2 output.raw

Apply resource limits to qemu-img operations
CPU time: 2 seconds maximum
Memory: 1 GB maximum
Validate images before processing
Use format inspection before passing to qemu-img
Reject images with backing files or external references
Only accept images from trusted sources
Keep systems updated
Apply security patches promptly
Monitor vendor security advisories
Use LUKS for encryption instead of native QCOW/QCOW2 encryption

OpenStack Specific¶

Enable conductor_always_validates_images = True for Ironic
Configure permitted_image_formats = raw,qcow2
Use the format_inspector module to pre-screen images
Disable image conversion in Glance if not required

oVirt Specific¶

Keep VDSM updated to latest version
Monitor Red Hat security advisories
Implement network segmentation for management networks

Proxmox Specific¶

Restrict API access for 'Sys.Audit' and 'VM.Monitor' privileges
Ensure 2FA is properly configured on Proxmox VE 8.1+
Only import disk images from trusted sources
Disable builder account on Kubernetes Image Builder VMs

Vulnerability Timeline¶

2008: CVE-2008-2004    - Format probing vulnerability (qemu-img)

2014: CVE-2014-0143    - Multiple block driver integer overflows
      CVE-2014-0144    - Block driver input validation
      CVE-2014-0145    - Block driver logic errors
      CVE-2014-0146    - QCOW2 NULL pointer dereference
      CVE-2014-0147    - QCOW2 snapshot crash
      CVE-2014-0148    - VHDX BAT entry flaw
      CVE-2014-0222/3  - QCOW1 integer overflows

2015: CVE-2015-1851    - Cinder format guessing
      CVE-2015-3456    - VENOM (qemu FDC buffer overflow)
      CVE-2015-5162    - Resource exhaustion DoS
      CVE-2015-5163    - QCOW2 backing file disclosure

2018: CVE-2018-10908   - VDSM qemu-img resource exhaustion

2019: CVE-2019-3831    - VDSM privilege escalation
      CVE-2019-3879    - oVirt API authorization bypass

2022: CVE-2022-35507   - Proxmox CRLF injection
      CVE-2022-35508   - Proxmox SSRF
      CVE-2022-47951   - VMDK flat descriptor file access

2023: CVE-2023-43320   - Proxmox 2FA bypass

2024: CVE-2024-4467    - qemu-img info json:{} vulnerability
      CVE-2024-21545   - Proxmox API file read
      CVE-2024-32498   - QCOW2 external data file access
      CVE-2024-40767   - Incomplete fix regression
      CVE-2024-44082   - Ironic image processing
      CVE-2024-9486    - K8s Image Builder default credentials