CVE-2022-26500: Veeam Backup & Replication RCE Flaw

CVE-2022-26500 Overview

CVE-2022-26500 is a path traversal vulnerability affecting Veeam Backup & Replication software versions 9.5U3, 9.5U4, 10.x, and 11.x. The vulnerability arises from improper limitation of path names, which allows remote authenticated users to access internal API functions. Successful exploitation enables attackers to upload and execute arbitrary code on affected systems, potentially leading to complete system compromise.

Critical Impact

This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Organizations using vulnerable Veeam Backup & Replication versions should prioritize immediate remediation.

Affected Products

• Veeam Backup & Replication 9.5U3 (version 9.5.0.1536)
• Veeam Backup & Replication 9.5U4 (version 9.5.4.2615)
• Veeam Backup & Replication 10.x (version 10.0.1.4854 and patches)
• Veeam Backup & Replication 11.x (version 11.0.1.1261 and patches)

Discovery Timeline

• 2022-03-17 - CVE-2022-26500 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2022-26500

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as a path traversal vulnerability. The flaw exists within the internal API functions of Veeam Backup & Replication, where insufficient validation of user-supplied path names allows authenticated attackers to escape intended directory restrictions.

The attack requires network access and valid authentication credentials, but once these prerequisites are met, the attacker can manipulate path parameters to access restricted API endpoints. The vulnerability chain enables both arbitrary file upload and subsequent code execution, making it particularly dangerous for enterprise backup infrastructure.

Root Cause

The root cause of CVE-2022-26500 lies in the insufficient sanitization of path name inputs within Veeam Backup & Replication's internal API. When processing requests, the application fails to properly validate and restrict directory traversal sequences (such as ../) in path parameters. This allows authenticated users to bypass intended directory boundaries and access sensitive API functions that should be restricted.

The lack of proper input validation and path canonicalization enables attackers to construct malicious requests that traverse outside the expected directory structure, ultimately gaining access to privileged functionality.

Attack Vector

The attack is conducted over the network against the Veeam Backup & Replication service. An authenticated attacker can craft specially formatted API requests containing directory traversal sequences to access internal API functions. Once access to these restricted functions is achieved, the attacker can upload malicious files to arbitrary locations on the system and execute them, resulting in remote code execution.

The attack flow typically involves:

1. Authenticating to the Veeam Backup & Replication service with valid credentials
2. Crafting API requests with path traversal sequences to access restricted internal functions
3. Uploading a malicious payload through the exposed API functionality
4. Executing the uploaded payload to achieve code execution on the target system

For technical exploitation details, refer to Veeam KB #4288.

Detection Methods for CVE-2022-26500

Indicators of Compromise

• Unusual API requests to Veeam Backup & Replication services containing path traversal sequences such as ../ or ..\\
• Unexpected file uploads or new executable files appearing in Veeam installation directories
• Authentication attempts followed by abnormal API activity patterns from the same source
• Suspicious outbound connections from Veeam Backup & Replication servers

Detection Strategies

• Monitor network traffic for HTTP/HTTPS requests to Veeam services containing directory traversal patterns
• Implement file integrity monitoring on Veeam Backup & Replication installation directories to detect unauthorized file modifications
• Review Veeam service logs for unusual API access patterns or authentication anomalies
• Deploy endpoint detection and response (EDR) solutions to identify suspicious process execution originating from Veeam services

Monitoring Recommendations

• Enable detailed logging for Veeam Backup & Replication API access and authentication events
• Configure SIEM rules to alert on directory traversal attempts targeting backup infrastructure
• Implement network segmentation monitoring to detect lateral movement from compromised backup servers
• Establish baseline behavior for Veeam services and alert on deviations

How to Mitigate CVE-2022-26500

Immediate Actions Required

• Identify all Veeam Backup & Replication installations running affected versions (9.5U3, 9.5U4, 10.x, 11.x)
• Apply the security patches provided by Veeam immediately, as this vulnerability is actively exploited
• Review authentication logs for any suspicious access to Veeam services
• Restrict network access to Veeam Backup & Replication management interfaces to authorized administrators only

Patch Information

Veeam has released security patches to address this vulnerability. Detailed patch information and remediation guidance is available in Veeam KB #4288. Organizations should upgrade to the latest patched versions of Veeam Backup & Replication immediately.

This vulnerability is listed in the CISA Known Exploited Vulnerabilities Catalog, which mandates federal agencies to remediate within specified timeframes. All organizations are strongly encouraged to treat this as a high-priority patching activity.

Workarounds

• If immediate patching is not possible, restrict network access to Veeam Backup & Replication services using firewall rules
• Implement strict authentication controls and audit user accounts with access to Veeam services
• Deploy web application firewall (WAF) rules to block requests containing directory traversal patterns
• Consider temporarily isolating backup infrastructure from the broader network until patches can be applied

# Example: Restrict access to Veeam services using Windows Firewall
# Limit access to trusted administrator IP addresses only
netsh advfirewall firewall add rule name="Restrict Veeam Management Access" dir=in action=allow protocol=tcp localport=9392 remoteip=10.0.0.0/24
netsh advfirewall firewall add rule name="Block Veeam External Access" dir=in action=block protocol=tcp localport=9392