CVE-2025-34255: CWE-204 Observable Response Discrepancy in D-Link Nuclias Connect
D-Link Nuclias Connect firmware versions <= 1.3.1.4 contain an observable response discrepancy vulnerability. The application's 'Forgot Password' endpoint returns distinct JSON responses depending on whether the supplied email address is associated with an existing account. Because the responses differ in the `data.exist` boolean value, an unauthenticated remote attacker can enumerate valid email addresses/accounts on the server. NOTE: D-Link states that a fix is under development.
AI Analysis
Technical Summary
CVE-2025-34255 is an information disclosure vulnerability in D-Link Nuclias Connect firmware versions <= 1.3.1.4. The 'Forgot Password' endpoint returns a JSON response containing a boolean field `data.exist` that differs based on the existence of the supplied email address in the system. This discrepancy enables unauthenticated remote attackers to enumerate valid user accounts by analyzing the response. The vulnerability is classified under CWE-204 (Observable Response Discrepancy). No official patch is currently available, but the vendor has stated that a fix is under development.
Potential Impact
An attacker can remotely and without authentication determine which email addresses are registered on the affected D-Link Nuclias Connect device. This account enumeration can facilitate targeted phishing or brute force attacks. There is no indication from the data that this vulnerability allows direct system compromise or data modification.
Mitigation Recommendations
Currently, no official patch or workaround is available as the vendor is still developing a fix. Users should monitor D-Link advisories for the release of an official update addressing this issue. Until a fix is provided, consider restricting access to the 'Forgot Password' endpoint or implementing rate limiting to reduce the risk of automated enumeration.
CVE-2025-34255: CWE-204 Observable Response Discrepancy in D-Link Nuclias Connect
Description
D-Link Nuclias Connect firmware versions <= 1.3.1.4 contain an observable response discrepancy vulnerability. The application's 'Forgot Password' endpoint returns distinct JSON responses depending on whether the supplied email address is associated with an existing account. Because the responses differ in the `data.exist` boolean value, an unauthenticated remote attacker can enumerate valid email addresses/accounts on the server. NOTE: D-Link states that a fix is under development.
CVSS v4.0
Score 6.9medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2025-34255 is an information disclosure vulnerability in D-Link Nuclias Connect firmware versions <= 1.3.1.4. The 'Forgot Password' endpoint returns a JSON response containing a boolean field `data.exist` that differs based on the existence of the supplied email address in the system. This discrepancy enables unauthenticated remote attackers to enumerate valid user accounts by analyzing the response. The vulnerability is classified under CWE-204 (Observable Response Discrepancy). No official patch is currently available, but the vendor has stated that a fix is under development.
Potential Impact
An attacker can remotely and without authentication determine which email addresses are registered on the affected D-Link Nuclias Connect device. This account enumeration can facilitate targeted phishing or brute force attacks. There is no indication from the data that this vulnerability allows direct system compromise or data modification.
Mitigation Recommendations
Currently, no official patch or workaround is available as the vendor is still developing a fix. Users should monitor D-Link advisories for the release of an official update addressing this issue. Until a fix is provided, consider restricting access to the 'Forgot Password' endpoint or implementing rate limiting to reduce the risk of automated enumeration.
Technical Details
- Data Version
- 5.1
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2025-04-15T19:15:22.578Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 68f140779f8a5dbaeaf6e5bb
Added to database: 10/16/2025, 18:59:03 UTC
Last enriched: 05/28/2026, 20:34:54 UTC
Last updated: 09/10/2026, 19:36:50 UTC
Views: 253
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.