CVE-2025-13044: IBM Concert Privilege Escalation Flaw

CVE-2025-13044 Overview

CVE-2025-13044 affects IBM Concert versions 1.0.0 through 2.2.0. The product creates temporary files with predictable names during normal operation. Local users can exploit this behavior to overwrite arbitrary files through a symbolic link (symlink) attack. The weakness is categorized under [CWE-340] Generation of Predictable Numbers or Identifiers.

The vulnerability requires local access but no authentication or user interaction. Successful exploitation impacts file integrity on the host system, while confidentiality and availability remain unaffected per the CVSS vector.

Critical Impact

A local attacker can overwrite arbitrary files writable by the IBM Concert process, potentially corrupting configuration data or replacing trusted binaries used by the application.

Affected Products

• IBM Concert 1.0.0
• IBM Concert versions between 1.0.0 and 2.2.0
• IBM Concert 2.2.0

Discovery Timeline

• 2026-04-07 - CVE-2025-13044 published to the National Vulnerability Database
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2025-13044

Vulnerability Analysis

IBM Concert generates temporary files using predictable naming patterns. When the application writes to these locations, it does not verify whether the target path is a regular file or a symbolic link. A local user who can write to the temporary directory can pre-create a symlink at the predicted path. The symlink points to a file the attacker wants to modify but cannot access directly.

When IBM Concert later writes to the predicted temporary filename, the operating system follows the symlink and writes to the attacker-chosen destination. The IBM Concert process executes the write under its own privileges, which may exceed those of the attacker. This pattern enables file overwrite outside the attacker's normal permission boundary.

Root Cause

The root cause is predictable temporary file naming combined with the absence of safe file creation flags. Secure implementations use randomized filenames and atomic creation with the O_CREAT | O_EXCL flag combination, or use APIs such as mkstemp(3). IBM Concert's logic permits an attacker to anticipate the filename and stage the symlink in advance.

Attack Vector

Exploitation requires local shell access on the host running IBM Concert. The attacker monitors or predicts the temporary filename pattern, creates a symbolic link from that path to a sensitive target file, and waits for IBM Concert to perform the write. No user interaction or elevated privileges are required to stage the attack. Refer to the IBM Support Page for vendor-specific technical context.

Detection Methods for CVE-2025-13044

Indicators of Compromise

• Symbolic links present in temporary directories used by IBM Concert that point to system configuration files, application binaries, or log files.
• Unexpected modifications to files owned by the IBM Concert service account with timestamps matching application activity.
• Audit log entries showing the IBM Concert process opening files outside its expected working directories.

Detection Strategies

• Monitor file creation events in temporary directories for symlink objects (lstat reporting S_IFLNK) preceding IBM Concert write operations.
• Enable Linux audit framework (auditd) rules on the IBM Concert temporary directory to log openat and symlinkat syscalls.
• Correlate process activity from the IBM Concert service with file integrity monitoring alerts on protected paths.

Monitoring Recommendations

• Deploy file integrity monitoring on configuration directories that the IBM Concert service account can reach.
• Alert on any non-administrative user creating symlinks inside directories used by privileged services.
• Review IBM Concert logs after deployment for unexpected file write failures, which may indicate exploitation attempts.

How to Mitigate CVE-2025-13044

Immediate Actions Required

• Apply the vendor-supplied fix referenced in the IBM Support Page for IBM Concert.
• Restrict shell access on hosts running IBM Concert to trusted administrative users only.
• Audit existing temporary directories for pre-staged symbolic links and remove any that are not legitimate.

Patch Information

IBM has published guidance for this issue on the IBM Support portal. Administrators should upgrade IBM Concert to a fixed release beyond version 2.2.0 as identified in the vendor advisory. Verify the patch level after deployment by checking the product version string against the IBM advisory.

Workarounds

• Configure a dedicated temporary directory for IBM Concert with restrictive permissions (chmod 700) and the sticky bit set.
• Run IBM Concert under a service account with the minimum file system permissions needed for operation.
• Mount the temporary filesystem with the nosymfollow option where supported by the kernel to block symlink traversal.

# Configuration example
sudo install -d -m 700 -o concert -g concert /var/tmp/concert
sudo mount -o remount,nosymfollow /var/tmp/concert
sudo auditctl -w /var/tmp/concert -p wa -k concert_tmp_watch