CVE-2026-24810

Product: RethinkDB
Affected versions: ≤ 2.4.4
Vulnerability type: Buffer Overflow (JSON parsing)
Impact: Remote Code Execution (RCE)
Severity: Critical
CVSS score: 10.0
Attack vector: Network
Authentication required: No
User interaction: None
Exploitability: High (low complexity, remotely reachable)

Official patch / upgrade (only authoritative link):
https://github.com/rethinkdb/rethinkdb/pull/7163

Executive Summary

A critical buffer overflow vulnerability exists in RethinkDB versions up to and including 2.4.4. The flaw resides in the JSON string parsing logic used by the database engine. When specially crafted Unicode escape sequences are processed, memory boundaries can be exceeded, resulting in memory corruption. Under the right conditions, this corruption can be abused to achieve remote code execution. The issue is remotely exploitable, does not require authentication, and affects any deployment that processes untrusted JSON input.

Immediate patching or upgrading is strongly recommended.

Technical Description

The vulnerability is caused by improper bounds checking during JSON string parsing, specifically while handling Unicode escape sequences (\uXXXX) and surrogate pairs during UTF-16 to UTF-8 conversion.

In vulnerable versions, malformed or truncated Unicode sequences may lead to incorrect buffer size calculations. As a result, more bytes are written into memory than were allocated, triggering a classic buffer overflow condition.

Because this code runs in the context of the RethinkDB server process, successful exploitation may allow attackers to overwrite adjacent memory structures, redirect execution flow, and potentially execute arbitrary code on the host system.

Affected Components

• Internal JSON parsing logic (cJSON-derived implementation)
• Any externally exposed RethinkDB interface that accepts JSON input
• Default database listener ports if exposed to untrusted networks

Exploitation Details (Educational Context Only)

Exploitation is performed by sending a specially crafted JSON payload to a vulnerable RethinkDB instance. The payload contains malformed Unicode escape sequences designed to confuse the parser’s memory allocation logic.

Typical exploitation characteristics:

• Use of incomplete or invalid \u escape sequences
• Malformed UTF-16 surrogate pairs (for example, high surrogates without matching low surrogates)
• Oversized JSON string values intended to stress buffer boundaries

If the payload is parsed, memory corruption may occur. With careful control of the overwritten data, this corruption can be escalated into remote code execution.

Note: At the time of analysis, no widely published exploit frameworks were observed. However, the vulnerability class is well-understood and historically exploitable. The absence of public exploit code should not be considered a mitigating factor.

Proof of Concept (PoC) Status

• Public PoC: Not broadly published
• Exploit maturity: Feasible with moderate effort by skilled attackers
• Risk assessment: High, due to simplicity of the trigger and remote reachability.

Indicators of Exploitation

The following symptoms may indicate active exploitation attempts or successful compromise:

• Sudden RethinkDB process crashes (segmentation faults)
• Unexpected restarts of the database service
• Core dump generation related to JSON parsing routines
• Abnormal CPU or memory usage following malformed requests
• Unexpected outbound network connections from the RethinkDB process

Detection and Monitoring Guidance

Network-Level Detection

Suspicious JSON payloads can be identified before reaching the database layer.

Key patterns to monitor:

• Presence of \u escape sequences not followed by exactly four hexadecimal characters
• Repeated or nested malformed Unicode sequences
• Unusually long JSON string fields sent to database endpoints
• URL-encoded representations of Unicode escapes (e.g., %5CuXXXX)

Example Detection Logic

• Flag JSON requests containing \u where the sequence is truncated or malformed
• Alert on single JSON string fields exceeding expected size thresholds
• Correlate malformed JSON requests with subsequent service crashes

Host-Level Detection

• Monitor system logs for segmentation faults or abnormal terminations of the RethinkDB process
• Watch for unexpected child processes spawned by the database service
• Track file system or permission changes initiated by the database user

Recommended Log Sources

• Network firewall / WAF logs
• Reverse proxy or load balancer request logs
• RethinkDB application logs
• System logs (syslog, journalctl)
• Process monitoring and crash dump logs

MITRE ATT&CK Mapping

• Initial Access: Exploit Public-Facing Application
• Execution: Exploitation for Privilege Escalation
• Impact: Arbitrary Code Execution / Service Compromise

Mitigation and Remediation

Immediate Actions

• Apply the official patch or upgrade to a fixed version that includes the correction
• Restrict network access to RethinkDB ports using firewall rules
• Ensure the database is not directly exposed to the internet

Short-Term Compensating Controls

• Place RethinkDB behind a strict reverse proxy or WAF
• Enforce JSON schema validation where possible
• Reject malformed Unicode escape sequences at the perimeter

Long-Term Hardening

• Follow least-privilege execution for database services
• Enable crash monitoring and alerting
• Perform regular fuzz testing on JSON interfaces
• Maintain timely patch management processes

Risk Rating Summary

This vulnerability represents a high-confidence, high-impact risk due to its remote nature, lack of authentication requirements, and potential for full system compromise. All exposed or internet-facing RethinkDB instances running vulnerable versions should be considered at immediate risk until patched.

Final Takeaway

This issue is not theoretical. It stems from a well-known class of memory safety flaws that have historically led to real-world compromises. Patching should be treated as urgent, and defensive monitoring should be enabled even after remediation to identify any prior or attempted exploitation.