CVE-2025-3486: Alltena Allegra RCE Vulnerability

CVE-2025-3486 Overview

CVE-2025-3486 is a directory traversal vulnerability in Alltena Allegra that allows authenticated remote attackers to execute arbitrary code on affected installations. The flaw resides in the isZipEntryValide method, which fails to properly validate user-supplied paths before using them in file operations. Successful exploitation grants code execution in the context of the LOCAL SERVICE account. The issue is tracked by the Zero Day Initiative as ZDI-CAN-25730 and classified under [CWE-22] (Improper Limitation of a Pathname to a Restricted Directory).

Critical Impact
Authenticated attackers can write arbitrary files outside intended directories through crafted ZIP archive entries, leading to remote code execution as LOCAL SERVICE on the Allegra host.

Affected Products

Alltena Allegra (versions prior to 8.1.2)
Allegra project management and tracking platform
Deployments exposing the ZIP import functionality

Discovery Timeline

2025-05-22 - CVE-2025-3486 published to NVD
2025-08-15 - Last updated in NVD database

Technical Details for CVE-2025-3486

Vulnerability Analysis

The vulnerability exists in Allegra's handling of ZIP archive uploads. The isZipEntryValide method is responsible for validating entries inside a user-supplied ZIP file before the application extracts them to disk. Because the validation logic does not adequately canonicalize or restrict path components, attackers can embed entries containing traversal sequences such as ../ to escape the intended extraction directory.

An authenticated attacker who can reach the ZIP import endpoint uploads a malicious archive. When the server processes the archive, files are written to attacker-chosen locations on the underlying file system. Writing executable content or web-accessible artifacts to sensitive paths yields code execution in the context of the LOCAL SERVICE account, which on Windows hosts can be leveraged to reach further internal services.

The network-reachable attack surface, low complexity, and the high confidentiality, integrity, and availability impact reflect this end-to-end path from authenticated upload to arbitrary code execution.

Root Cause

The root cause is improper validation of pathnames in isZipEntryValide. The method does not reject ZIP entries whose resolved paths fall outside the designated extraction directory. This is a classic Zip Slip pattern, mapped to [CWE-22]. Canonical path comparison against the target base directory is missing, so traversal payloads are accepted as legitimate entries.

Attack Vector

Exploitation requires valid Allegra credentials but no user interaction beyond the attacker's own session. The attacker crafts a ZIP archive in which one or more entries use relative traversal sequences in their file names. The archive is submitted to the import functionality. Allegra invokes isZipEntryValide, which approves the entries, and the server extracts attacker-controlled files to arbitrary filesystem locations. Placing an executable, library, or script in a path used by the application or operating system results in code execution as LOCAL SERVICE.

For full technical details, see the Zero Day Initiative Advisory ZDI-25-255.

Detection Methods for CVE-2025-3486

Indicators of Compromise

ZIP uploads to Allegra import endpoints containing entry names with ../ or absolute path prefixes
Files appearing under Allegra installation, web root, or system directories with recent timestamps that do not match deployment activity
New or modified executables, DLLs, or scripts owned by the LOCAL SERVICE account on Allegra hosts
Outbound network connections initiated by the Allegra service process after a ZIP import event

Detection Strategies

Inspect application and web server logs for authenticated POST requests to ZIP import endpoints, correlating with subsequent filesystem writes outside the designated extraction directory.
Apply file integrity monitoring to Allegra binaries, configuration paths, and adjacent system directories to surface unauthorized writes.
Hunt for process spawns from the Allegra Java or web server process tree, particularly child processes such as cmd.exe, powershell.exe, or shell utilities running as LOCAL SERVICE.

Monitoring Recommendations

Forward Allegra application logs, Windows Security and Sysmon events, and web server access logs to a centralized analytics platform for correlation.
Alert on ZIP archive entries whose resolved paths exit the intended extraction root during decompression by any service account.
Track authentication events for Allegra accounts to detect credential abuse that could precede exploitation of this vulnerability.

How to Mitigate CVE-2025-3486

Immediate Actions Required

Upgrade Allegra to release 8.1.2 or later, which addresses the isZipEntryValide path validation flaw.
Restrict network access to the Allegra management interface using firewalls, VPNs, or reverse proxies until patching is complete.
Audit Allegra user accounts and rotate credentials for any account with import or administrative privileges.
Review the Allegra host filesystem for files written outside expected directories since the platform was deployed.

Patch Information

Alltena addressed the issue in Allegra release 8.1.2. Refer to the Alltena Release Notes 8.1.2 for upgrade instructions and version-specific changes. Administrators should validate the patched version after upgrade and confirm the isZipEntryValide behavior rejects traversal entries.

Workarounds

Limit accounts permitted to upload or import ZIP archives in Allegra to a minimal, trusted set of administrators.
Place Allegra behind a web application firewall configured to block requests containing path traversal sequences in upload payloads.
Run the Allegra service with the least privileges required and isolate it from sensitive network segments to reduce blast radius if exploited.

bash

# Verify installed Allegra version and confirm upgrade to 8.1.2 or later
curl -sk https://allegra.example.local/login | grep -i "version"

# Example WAF rule (ModSecurity) blocking traversal in multipart uploads
SecRule FILES_NAMES|ARGS_NAMES|REQUEST_BODY "@rx (\.\./|\.\.\\)" \
  "id:1003486,phase:2,deny,status:400,log,msg:'Blocked path traversal attempt (CVE-2025-3486)'"