CVE-2022-24963 Overview
CVE-2022-24963 is an integer overflow vulnerability [CWE-190] in the apr_encode family of functions within Apache Portable Runtime (APR) version 1.7.0. The flaw allows an attacker to write beyond the bounds of an allocated buffer, resulting in heap memory corruption. Because APR underpins Apache HTTP Server and many downstream projects, the impact reaches a wide ecosystem of network-facing applications.
The vulnerability carries a CVSS 3.1 score of 9.8 and can be exploited remotely without authentication or user interaction. Successful exploitation can lead to arbitrary code execution, data tampering, or denial of service in any process linking the affected APR library.
Critical Impact
Remote, unauthenticated attackers can trigger an out-of-bounds write in APR 1.7.0, leading to potential code execution in dependent services such as Apache HTTP Server.
Affected Products
- Apache Portable Runtime (APR) version 1.7.0
- Applications and services statically or dynamically linked against APR 1.7.0
- NetApp products bundling vulnerable APR releases (see NetApp advisory NTAP-20230908-0008)
Discovery Timeline
- 2023-01-31 - CVE-2022-24963 published to the National Vulnerability Database
- 2023-09-08 - NetApp publishes security advisory NTAP-20230908-0008
- 2025-03-27 - Last updated in NVD database
Technical Details for CVE-2022-24963
Vulnerability Analysis
The vulnerability resides in the apr_encode functions introduced in APR 1.7.0. These routines perform encoding operations such as Base64 and Base32 transformations and calculate output buffer sizes from caller-supplied lengths. The size calculation can overflow when an attacker provides sufficiently large input lengths.
When the integer overflow occurs, the computed buffer size wraps to a small value. The function then allocates a buffer smaller than the data actually written, producing a heap-based out-of-bounds write. An attacker who controls the input length and content can corrupt adjacent heap structures.
Because APR is a foundational library used by Apache HTTP Server, Subversion, and other network services, exploitation can occur over the network without authentication. The result is a deterministic buffer overflow primitive suitable for code execution depending on the calling application.
Root Cause
The root cause is an unchecked arithmetic operation during output length computation in the apr_encode_* helper routines. Multiplying or adding input length values produces a value larger than SIZE_MAX, which wraps to a small allocation size. The encoder then writes the full encoded payload into the undersized buffer.
Attack Vector
Exploitation requires an attacker to reach a code path that invokes an apr_encode function with attacker-controlled input length. In server contexts this can be achieved through crafted HTTP requests, WebDAV operations, or protocol fields that downstream applications pass to APR encoding routines. No authentication or user interaction is required.
The vulnerability is described in prose only. Refer to the Apache Mailing List Thread for the upstream technical discussion.
Detection Methods for CVE-2022-24963
Indicators of Compromise
- Crashes or segmentation faults in processes linking libapr-1.so.0, particularly during encoding operations
- Unexpected child process termination in httpd workers with heap corruption signatures in core dumps
- Abnormally large request payloads or header values targeting endpoints that invoke Base64 or Base32 encoding paths
Detection Strategies
- Inventory all hosts running APR 1.7.0 using software composition analysis or package managers (rpm -q apr, dpkg -l apr)
- Monitor for repeated worker crashes correlated with inbound requests carrying oversized encoded fields
- Apply runtime memory-safety instrumentation such as AddressSanitizer in non-production environments to catch out-of-bounds writes
Monitoring Recommendations
- Enable verbose error logging on Apache HTTP Server and forward logs to a centralized analytics platform for anomaly review
- Alert on segmentation faults and abnormal exit codes from APR-linked services
- Track outbound network connections from web server processes to identify post-exploitation behavior
How to Mitigate CVE-2022-24963
Immediate Actions Required
- Upgrade Apache Portable Runtime to version 1.7.1 or later, which removes the vulnerable encoding logic
- Rebuild and redeploy any application statically linked against APR 1.7.0
- Apply vendor-specific patches for bundled products, including those listed in NetApp Security Advisory NTAP-20230908-0008
Patch Information
The Apache Software Foundation addressed the issue in APR 1.7.1 by adding bounds checks to the apr_encode length computations. Refer to the Apache Mailing List Thread for the upstream announcement and source-level remediation details.
Workarounds
- Restrict network exposure of services that link APR 1.7.0 until patches can be applied
- Place affected services behind a web application firewall configured to reject oversized request fields
- Disable application features that invoke apr_encode Base64 or Base32 routines on untrusted input where feasible
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
