CVE-2022-1253: Libde265 Buffer Overflow Vulnerability

CVE-2022-1253 Overview

CVE-2022-1253 is a heap-based buffer overflow vulnerability affecting the libde265 library, an open-source HEVC (H.265) video codec implementation developed by struktur AG. This vulnerability exists in versions prior to and including 1.0.8 of the library. The flaw occurs due to improper validation of the cpb_cnt_minus1 parameter in the VUI (Video Usability Information) parsing code, which can lead to out-of-bounds memory access.

Critical Impact

This heap-based buffer overflow allows remote attackers to potentially execute arbitrary code or cause denial of service through specially crafted HEVC video files processed by applications using the vulnerable libde265 library.

Affected Products

• struktur libde265 versions up to and including 1.0.8
• Applications and media players utilizing libde265 for HEVC decoding
• Linux distributions packaging vulnerable libde265 versions (including Debian)

Discovery Timeline

• April 6, 2022 - CVE CVE-2022-1253 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-1253

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). The flaw resides in the VUI parameter parsing functionality within libde265's HEVC decoder. When parsing HEVC video streams, the library processes Video Usability Information (VUI) parameters embedded in the Sequence Parameter Set (SPS). The vulnerability was identified through OSS-Fuzz testing (issue 27590), which discovered that malformed input could trigger out-of-bounds memory operations.

The attack can be initiated remotely through the network by providing a maliciously crafted HEVC video file to any application utilizing the vulnerable libde265 library. No authentication or user interaction is required to exploit this vulnerability, and successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of this vulnerability lies in the insufficient validation of the cpb_cnt_minus1 parameter within the vui.cc file. The HEVC specification defines that this value should not exceed 31, but the vulnerable code did not enforce this boundary check. Additionally, the sps.cc file failed to properly handle error conditions returned from VUI parsing operations, allowing the vulnerability to propagate even when errors occurred.

Attack Vector

The attack vector for CVE-2022-1253 is network-based. An attacker can exploit this vulnerability by:

1. Crafting a malicious HEVC video file with an out-of-range cpb_cnt_minus1 value (greater than 31)
2. Delivering the malicious file to a victim through various means (web content, email attachments, file sharing)
3. When the victim's application attempts to decode the video using libde265, the heap buffer overflow is triggered
4. Depending on memory layout and exploitation techniques, this could lead to code execution or denial of service

The security patch addresses this by implementing proper boundary validation:

     if (!low_delay_hrd_flag[i])
     {
       READ_VLC_OFFSET(cpb_cnt_minus1[i], uvlc, 0);
+      if (cpb_cnt_minus1[i] > 31) {
+	return DE265_ERROR_CODED_PARAMETER_OUT_OF_RANGE;
+      }
     }

     for (nalOrVcl = 0; nalOrVcl < 2; nalOrVcl++)

Source: GitHub Commit

Additionally, the fix ensures proper error propagation in the SPS parsing:

 
   vui_parameters_present_flag = get_bits(br,1);
   if (vui_parameters_present_flag) {
-    vui.read(errqueue, br, this);
+    de265_error err = vui.read(errqueue, br, this);
+    if (err) {
+      return err;
+    }
   }

 

Source: GitHub Commit

Detection Methods for CVE-2022-1253

Indicators of Compromise

• Unexpected crashes or abnormal termination of applications using libde265 for HEVC decoding
• Memory corruption errors or segmentation faults in media processing applications
• Suspicious HEVC video files with malformed VUI parameters in the SPS NAL units
• Unusual heap memory allocation patterns in applications handling video content

Detection Strategies

• Implement file integrity monitoring for libde265 library files to detect unauthorized modifications
• Deploy application-level monitoring to detect abnormal behavior during video processing operations
• Use memory corruption detection tools (AddressSanitizer, Valgrind) in development and testing environments
• Monitor for crash reports and core dumps from media processing applications that may indicate exploitation attempts

Monitoring Recommendations

• Enable verbose logging for media processing applications to capture decoding errors
• Implement network traffic analysis to identify potential delivery of malicious HEVC files
• Set up alerting for repeated crashes in applications utilizing libde265
• Monitor system resource usage for anomalies during video file processing

How to Mitigate CVE-2022-1253

Immediate Actions Required

• Update libde265 to a version containing commit 8e89fe0e175d2870c39486fdd09250b230ec10b8 or later
• Review and update all applications that bundle or depend on libde265
• Apply vendor patches from your Linux distribution (e.g., Debian DSA-5346)
• Consider temporarily disabling HEVC video processing if immediate patching is not possible

Patch Information

The vulnerability has been addressed in commit 8e89fe0e175d2870c39486fdd09250b230ec10b8 in the libde265 repository. However, at the time of the CVE publication, this fix was not yet included in an official release. Users should verify their libde265 version and apply updates from their distribution vendors.

For Debian users, the Debian Security Advisory DSA-5346 provides patched packages. Additional details about the vulnerability and the fix can be found in the Huntr Bounty Notification and the GitHub Commit.

Workarounds

• Restrict processing of untrusted HEVC video files until patching is completed
• Implement input validation at the application level to reject suspicious video files before passing to libde265
• Run applications using libde265 in sandboxed environments with limited privileges
• Deploy network-level filtering to block delivery of potentially malicious video content

# Check installed libde265 version on Debian/Ubuntu systems
dpkg -l | grep libde265

# Update libde265 on Debian/Ubuntu
sudo apt update && sudo apt upgrade libde265-0

# For source installations, verify the commit hash includes the security fix
cd /path/to/libde265
git log --oneline | grep 8e89fe0e175d2870c39486fdd09250b230ec10b8