Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-28678 is a vulnerability in the DSA Study Hub's user authentication system where JSON Web Tokens (JWTs) used for authentication were stored in HTTP cookies without encryption. This means the tokens were stored as clear-text (base64-encoded) in cookies, making them susceptible to interception or unauthorized access."}, {'type': 'paragraph', 'content': 'Because the JWT payloads were not cryptographically protected, attackers could potentially intercept these tokens over the network or access them from the client-side cookie store, allowing them to impersonate users and access protected data.'}, {'type': 'paragraph', 'content': 'The vulnerability was fixed by encrypting the JWT tokens before storing them in cookies using AES-256 encryption, ensuring the confidentiality and integrity of the tokens.'}] [1, 2]

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Impact Analysis

This vulnerability can have serious security impacts including unauthorized access to user accounts and protected application data.

• Attackers can intercept JWT tokens over the network if the connection is not secure.
• Attackers who gain access to client-side cookies can read and manipulate the tokens.
• With stolen or manipulated tokens, attackers can impersonate legitimate users, potentially leading to data breaches or unauthorized actions within the application.

The vulnerability has a high severity score (CVSS 8.1) indicating a significant risk with low attack complexity and no privileges required.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by inspecting the HTTP cookies used for authentication tokens (JWTs) to check if they are stored in plaintext without encryption.'}, {'type': 'paragraph', 'content': 'One approach is to capture network traffic or inspect cookies in the browser or server to see if JWT tokens are stored as base64-encoded strings without cryptographic protection.'}, {'type': 'paragraph', 'content': 'Suggested commands include using network traffic analysis tools like tcpdump or Wireshark to capture HTTP traffic and grep or similar tools to search for JWT tokens in cookies.'}, {'type': 'list_item', 'content': "Use tcpdump to capture HTTP traffic on port 80 or 443 (if not encrypted): tcpdump -i <interface> -A 'tcp port 80 or 443'"}, {'type': 'list_item', 'content': "Extract cookies from captured traffic and search for JWT tokens: grep 'accessToken=' capturefile.pcap"}, {'type': 'list_item', 'content': 'In a browser, inspect cookies for the application domain and check if the JWT token appears as a readable base64 string without encryption.'}, {'type': 'paragraph', 'content': 'If tokens are found in plaintext form, the system is vulnerable. If tokens appear encrypted or unreadable, the patch has likely been applied.'}] [1, 2]

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Mitigation Strategies

To mitigate this vulnerability immediately, update the affected software to version 1.0 or later where the issue has been patched.

The patch involves encrypting JWT tokens stored in HTTP cookies using AES-256 encryption to prevent exposure of sensitive token payloads.

• Apply the commit d527fba or upgrade to the fixed version of the dsa-hub-server package.
• Ensure that the environment variable COOKIE_SECRET is set to a strong secret to enable proper encryption key derivation.
• Verify that the authentication middleware correctly decrypts and verifies JWT tokens from encrypted cookies.

Additionally, enforce secure cookie flags such as httpOnly, secure (in production), and sameSite policies to reduce risk.

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