CVE-2024-53693: QNAP QTS CRLF Injection Vulnerability

CVE-2024-53693 Overview

QNAP disclosed a Carriage Return Line Feed (CRLF) injection vulnerability affecting multiple versions of the QTS and QuTS hero network-attached storage (NAS) operating systems. The flaw stems from improper neutralization of CRLF sequences in HTTP-facing components, tracked under [CWE-93] and [CWE-94]. Authenticated remote attackers with user-level access can inject CRLF characters to modify application data on affected appliances. QNAP addressed the issue in QTS 5.2.3.3006 build 20250108 and QuTS hero h5.2.3.3006 build 20250108. Details were published in QNAP Security Advisory QSA-24-54.

Critical Impact
Authenticated remote attackers can inject CRLF sequences to modify application data on QNAP NAS appliances, undermining data integrity on storage systems.

Affected Products

QNAP QTS versions from 5.2.0.2737 through 5.2.2.2950 prior to 5.2.3.3006 build 20250108
QNAP QuTS hero versions from h5.2.0.2737 through h5.2.2.2952 prior to h5.2.3.3006 build 20250108
QNAP NAS appliances running the affected QTS and QuTS hero operating systems

Discovery Timeline

2025-03-07 - CVE-2024-53693 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2024-53693

Vulnerability Analysis

The vulnerability is a CRLF injection issue in the QTS and QuTS hero operating systems. QNAP classifies the weakness under [CWE-93] (Improper Neutralization of CRLF Sequences) and [CWE-94] (Improper Control of Generation of Code). Affected components accept user-controlled input that is later embedded in protocol or application data structures without stripping \r\n sequences. Attackers with valid user credentials can supply crafted input that terminates the current context and injects additional fields or records.

Successful exploitation allows modification of application data managed by the NAS. The vector is network-based and requires low attack complexity, but authentication is required, limiting exposure to accounts with existing access. The scope is limited to integrity of the application itself; confidentiality and system availability outside the affected component are not directly impacted according to QNAP's advisory.

Root Cause

The underlying defect is missing sanitization of newline characters in input handling routines. When CRLF pairs pass through to downstream serializers, log writers, or HTTP response builders, they break framing and let attackers append attacker-chosen content. This is a classic output-encoding failure where trust boundaries between user input and protocol data are not enforced.

Attack Vector

Exploitation requires an authenticated session on the NAS management interface. The attacker submits a request containing CRLF characters in a parameter that is reflected into a response header, log entry, or persisted application record. The injected sequence forces the parser to treat subsequent bytes as new headers, fields, or records, altering stored or transmitted data.

No verified proof-of-concept exploit is publicly available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the QNAP Security Advisory QSA-24-54 for vendor-provided technical details.

Detection Methods for CVE-2024-53693

Indicators of Compromise

HTTP request bodies or query strings on the NAS management interface containing encoded CRLF sequences such as %0d%0a, \r\n, or \\u000d\\u000a
Unexpected header entries or duplicated fields in QTS/QuTS hero application logs following authenticated user sessions
Modifications to configuration or application records that do not correspond to legitimate administrative activity

Detection Strategies

Inspect web server and reverse-proxy logs in front of the NAS for URL-encoded newline characters submitted by authenticated users
Correlate authenticated management sessions with anomalous configuration writes or log-entry structures on the QTS/QuTS hero appliance
Baseline expected HTTP header patterns on the management interface and alert on deviations that suggest header injection

Monitoring Recommendations

Forward QTS and QuTS hero system, access, and audit logs to a centralized log platform for retention and query
Enable alerting on repeated failed input validation events or malformed requests targeting the management console
Track version strings reported by NAS devices and flag hosts still running builds prior to 5.2.3.3006 build 20250108

How to Mitigate CVE-2024-53693

Immediate Actions Required

Upgrade QTS to 5.2.3.3006 build 20250108 or later, and QuTS hero to h5.2.3.3006 build 20250108 or later
Restrict management-interface exposure to trusted internal networks and VPN users, removing direct internet accessibility
Review NAS user accounts and revoke or rotate credentials for accounts that no longer require access

Patch Information

QNAP has resolved the vulnerability in QTS 5.2.3.3006 build 20250108 and QuTS hero h5.2.3.3006 build 20250108. Administrators should apply the fix through the QTS App Center or Control Panel firmware update workflow. Reference the QNAP Security Advisory QSA-24-54 for the authoritative patch guidance.

Workarounds

Enforce strong, unique passwords and multi-factor authentication on all NAS user and administrative accounts to reduce the pool of accounts that could exploit the flaw
Place the NAS management interface behind a reverse proxy or firewall that strips or rejects requests containing raw CRLF sequences
Disable unused services and applications on the NAS to reduce the reachable attack surface until patching is complete

bash

# Verify current QTS or QuTS hero build from the NAS shell
getcfg System Version
getcfg System "Build Number"

# Confirm the running build is at or above the fixed version:
# QTS      >= 5.2.3.3006 build 20250108
# QuTS hero >= h5.2.3.3006 build 20250108