CVE-2026-2889 Overview
A use after free vulnerability has been identified in CCExtractor versions up to 0.96.5. The vulnerability exists in the processmp4 function within the src/lib_ccx/mp4.c library file. This memory corruption flaw can be triggered through manipulation of MP4 file processing, potentially leading to application crashes or memory corruption. The exploit for this vulnerability has been publicly disclosed, making it critical for users to upgrade to the patched version immediately.
Critical Impact
Local attackers can exploit this use after free vulnerability in CCExtractor's MP4 processing functionality, potentially causing denial of service through memory corruption. A public exploit is available.
Affected Products
- CCExtractor versions up to 0.96.5
- Applications and systems utilizing CCExtractor library for caption extraction
- Media processing pipelines incorporating vulnerable CCExtractor versions
Discovery Timeline
- 2026-02-21 - CVE CVE-2026-2889 published to NVD
- 2026-02-23 - Last updated in NVD database
Technical Details for CVE-2026-2889
Vulnerability Analysis
This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the processmp4 function within the src/lib_ccx/mp4.c file, which handles MP4 file parsing for closed caption extraction. The vulnerability occurs due to improper memory management during MP4 file processing operations.
The attack requires local access to the system running the vulnerable CCExtractor software. An attacker could craft a malicious MP4 file that, when processed by CCExtractor, triggers the use after free condition. This could lead to memory corruption, application crashes, or potentially arbitrary code execution in certain scenarios.
Root Cause
The root cause of this vulnerability stems from insufficient validation in the MP4 processing code. Specifically, the processmp4 function lacked proper null pointer validation before proceeding with file operations. Additionally, related functions parse_PAT and parse_PMT in src/lib_ccx/ts_tables.c were susceptible to heap overflow conditions due to inadequate boundary checking when processing ES_info_length values against buffer bounds.
Attack Vector
The attack vector requires local access to the target system. An attacker must be able to provide a maliciously crafted MP4 file to the CCExtractor application for processing. The exploit is publicly available, which increases the risk of exploitation. The attack does not require user interaction beyond the initial file processing, and the attacker needs low-level privileges on the system.
The security patch addresses these issues by adding null pointer validation and boundary checks:
#endif
memset(&dec_sub, 0, sizeof(dec_sub));
+ if (file == NULL)
+ {
+ mprint("Error: NULL file path provided to processmp4\n");
+ return -1;
+ }
mprint("Opening \'%s\': ", file);
#ifdef MP4_DEBUG
gf_log_set_tool_level(GF_LOG_CONTAINER, GF_LOG_DEBUG);
Source: GitHub Commit Details
The related heap overflow fix in ts_tables.c:
{
// if this any generally used video stream tyoe get clashed with ATSC/SCTE standard
// then this code can go in some atsc flag
+ // Validate ES_info_length against buffer bounds to prevent heap overflow
+ if (i + 5 + ES_info_length > len)
+ break;
+
unsigned char *es_info = buf + i + 5;
- for (desc_len = 0; (buf + i + 5 + ES_info_length) > es_info; es_info += desc_len)
+ unsigned char *es_info_end = buf + i + 5 + ES_info_length;
+ for (desc_len = 0; es_info_end > es_info; es_info += desc_len)
{
+ // Need at least 2 bytes for descriptor_tag and desc_len
+ if (es_info + 2 > es_info_end)
+ break;
+
enum ccx_mpeg_descriptor descriptor_tag = (enum ccx_mpeg_descriptor)(*es_info++);
int nb_service;
int is_608;
Source: GitHub Commit Details
Detection Methods for CVE-2026-2889
Indicators of Compromise
- Unexpected crashes or segmentation faults in CCExtractor during MP4 file processing
- Abnormal memory consumption patterns when processing media files
- Core dumps or error logs indicating memory access violations in processmp4 or related functions
- Suspicious MP4 files with malformed structure in processing queues
Detection Strategies
- Monitor CCExtractor process behavior for signs of memory corruption or abnormal termination
- Implement file integrity monitoring on systems running CCExtractor to detect potentially malicious input files
- Review application logs for error messages related to null pointer access or buffer operations
- Deploy endpoint detection solutions to identify exploitation attempts targeting memory corruption vulnerabilities
Monitoring Recommendations
- Enable verbose logging in CCExtractor to capture detailed processing information
- Monitor system logs for CCExtractor-related crashes and memory errors
- Implement alerting for unusual resource consumption during media file processing
- Track file sources and validate input files before processing with CCExtractor
How to Mitigate CVE-2026-2889
Immediate Actions Required
- Upgrade CCExtractor to version 0.96.6 or later immediately
- Audit systems to identify all instances of vulnerable CCExtractor installations
- Restrict local access to systems running CCExtractor to authorized users only
- Validate and sanitize all MP4 files before processing with CCExtractor
Patch Information
The vulnerability has been addressed in CCExtractor version 0.96.6. The fix is contained in commit fd7271bae238ccb3ae8a71304ea64f0886324925, which adds proper null pointer validation and boundary checking to prevent the use after free and heap overflow conditions.
Upgrade resources:
Workarounds
- If immediate upgrade is not possible, restrict access to the CCExtractor binary to trusted users only
- Implement input validation to filter potentially malicious MP4 files before processing
- Run CCExtractor in a sandboxed environment with restricted permissions to limit impact of exploitation
- Consider using alternative caption extraction tools until the upgrade can be completed
# Configuration example
# Upgrade CCExtractor to patched version
# Option 1: Download latest release
wget https://github.com/CCExtractor/ccextractor/releases/download/v0.96.6/ccextractor-0.96.6.tar.gz
tar -xzf ccextractor-0.96.6.tar.gz
cd ccextractor-0.96.6
./configure && make && sudo make install
# Option 2: Build from source with the security patch
git clone https://github.com/CCExtractor/ccextractor.git
cd ccextractor
git checkout v0.96.6
cd linux
./build && sudo ./install
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