CVE-2026-1109: librtsp Buffer Overflow Vulnerability

CVE-2026-1109 Overview

A buffer overflow vulnerability has been identified in the cijliu librtsp library, specifically affecting the rtsp_parse_request function. This vulnerability allows a local attacker with low privileges to manipulate input data in a way that causes a buffer overflow condition, potentially leading to memory corruption and system instability.

Critical Impact

Local attackers can exploit the buffer overflow in rtsp_parse_request to corrupt memory, potentially affecting confidentiality, integrity, and availability of systems using the vulnerable librtsp library.

Affected Products

• cijliu librtsp (up to commit 2ec1a81ad65280568a0c7c16420d7c10fde13b04)
• Applications and systems utilizing the vulnerable librtsp library
• RTSP-based streaming implementations built on affected versions

Discovery Timeline

• January 18, 2026 - CVE-2026-1109 published to NVD
• January 18, 2026 - Last updated in NVD database

Technical Details for CVE-2026-1109

Vulnerability Analysis

The vulnerability resides in the rtsp_parse_request function within the librtsp library. This function is responsible for parsing incoming RTSP (Real Time Streaming Protocol) requests. Due to improper bounds checking during the parsing operation, the function fails to adequately validate the size of input data before copying it into a fixed-size buffer.

This improper restriction of operations within the bounds of a memory buffer (CWE-119) creates a classic buffer overflow condition. When specially crafted input exceeding the expected buffer size is processed, it overwrites adjacent memory regions, potentially corrupting critical data structures or control flow information.

The librtsp project follows a rolling release model, meaning there are no discrete version numbers to track. The vulnerability affects all commits up to and including 2ec1a81ad65280568a0c7c16420d7c10fde13b04. The vendor was contacted regarding this disclosure but did not respond.

Root Cause

The root cause of this vulnerability is insufficient input validation in the rtsp_parse_request function. The function does not properly verify that incoming RTSP request data fits within the allocated buffer boundaries before performing memory operations. This lack of bounds checking allows data to overflow the designated buffer space when parsing malformed or oversized RTSP requests.

Attack Vector

This vulnerability requires local access to exploit. An attacker with local system access and low-level privileges can craft malicious RTSP request data that, when processed by the vulnerable rtsp_parse_request function, triggers the buffer overflow. The attack does not require user interaction and can be executed with minimal complexity.

The exploitation involves sending specially crafted RTSP protocol messages with oversized fields that exceed the buffer capacity allocated for parsing. When the vulnerable function processes this input without adequate size validation, the excess data overwrites adjacent memory, potentially allowing the attacker to manipulate program execution or cause denial of service.

Technical details and proof-of-concept information are available in the GitHub PoC Repository.

Detection Methods for CVE-2026-1109

Indicators of Compromise

• Unexpected crashes or segmentation faults in applications using librtsp
• Abnormal memory consumption patterns in RTSP-processing services
• Core dumps indicating memory corruption in rtsp_parse_request or related functions
• System logs showing repeated failures in RTSP request parsing operations

Detection Strategies

• Monitor application logs for errors related to RTSP request parsing failures
• Implement memory corruption detection tools (AddressSanitizer, Valgrind) during testing
• Deploy runtime protection mechanisms that detect buffer overflow attempts
• Review source code dependencies for the affected librtsp commit hash 2ec1a81ad65280568a0c7c16420d7c10fde13b04

Monitoring Recommendations

• Configure system monitoring to alert on abnormal process terminations involving RTSP services
• Implement file integrity monitoring on librtsp library files to detect unauthorized modifications
• Enable enhanced logging for RTSP-based applications to capture parsing anomalies
• Deploy SentinelOne Singularity agents for real-time memory exploitation detection and response

How to Mitigate CVE-2026-1109

Immediate Actions Required

• Audit systems to identify applications using the vulnerable librtsp library
• Restrict local access to systems running RTSP services to trusted users only
• Consider disabling or isolating affected RTSP functionality until a patch is available
• Implement additional input validation layers at the application level if possible

Patch Information

As of the last update, the vendor (cijliu) has not responded to disclosure communications, and no official patch is available. The librtsp project uses a rolling release model, so users should monitor the project repository for commits that address this buffer overflow in the rtsp_parse_request function.

Additional vulnerability details are available through VulDB #341701 and the VulDB CTI Entry.

Workarounds

• Limit local access to systems running applications that use librtsp
• Run RTSP services in sandboxed or containerized environments to limit blast radius
• Implement network segmentation to isolate RTSP-processing systems from critical infrastructure
• Consider alternative RTSP libraries with active security maintenance until a fix is available

# Configuration example - Restrict access to RTSP service user
# Create dedicated service account with minimal privileges
useradd -r -s /sbin/nologin rtsp_service

# Set restrictive permissions on librtsp directory
chmod 750 /path/to/librtsp
chown -R rtsp_service:rtsp_service /path/to/librtsp

# Run RTSP application with reduced privileges
sudo -u rtsp_service /path/to/rtsp_application