CVE-2026-52394

Deferred Deferred - Pending Action

Incorrect Access Control in DeepSeek V4

Publication date: 2026-10-13

Last updated on: 2026-10-16

Assigner: MITRE

Description

DeepSeek V4 is vulnerable to Incorrect Access Control via a crafted input.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-10-13

Last Modified

2026-10-16

Generated

2026-10-19

AI Q&A

2026-10-13

EPSS Evaluated

2026-10-18

NVD

CVE-2026-52394

EUVD

EUVD-2026-98960

Affected Vendors & Products

Vendor	Product	Version / Range
n/a	n/a	n/a

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-209	The product generates an error message that includes sensitive information about its environment, users, or associated data.
CWE-201	The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

Attack-Flow Graph

Executive Summary

CVE-2026-52394 is an Incorrect Access Control vulnerability in DeepSeek V4's chat interface. It allows an unauthenticated attacker to bypass session isolation and access reasoning chain data from other users' conversations by sending a malformed input containing a specific string to the chat interface.

Detection Guidance

Monitor network traffic to chat.deepseek.com for malformed inputs containing the string '??<think ????????????'. Check server logs for unusual reasoning chain data exposure or unauthorized access patterns in the chat interface.

Impact Analysis

This vulnerability could expose sensitive information such as prompts or intermediate reasoning steps from other users' sessions. If you use DeepSeek V4's chat interface, your data might be accessible to unauthorized parties.

Compliance Impact

This vulnerability could lead to unauthorized exposure of sensitive user data, including prompts and reasoning steps from other sessions. This may violate GDPR's data protection principles and HIPAA's confidentiality requirements if personal or health-related information is leaked.

Mitigation Strategies

Apply vendor patches for DeepSeek V4 to enforce stricter session isolation. Validate and sanitize all inputs to the chat interface, particularly thought trigger formats. Restrict access to the chat interface if possible and monitor for suspicious activity.

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