Unauthenticated memory corruption via negative Content-Length
Published Jun 16, 2025 · Updated Jun 16, 2025
Stack-based buffer overflow in D-Link DIR-632 FW103B08 allows remote attackers to corrupt memory through an HTTP POST request. The get_pure_content function passes a negative Content-Length to safe_fread, where unsigned conversion produces an oversized read despite a 1,200-byte cap. No authentication or user interaction is required; exploitation can crash the router or corrupt control data, while code execution is not demonstrated.
Summary
What happened
Stack-based buffer overflow in D-Link DIR-632 FW103B08 allows remote attackers to corrupt memory through an HTTP POST request. The get_pure_content function passes a negative Content-Length to safe_fread, where unsigned conversion produces an oversized read despite a 1,200-byte cap. No authentication or user interaction is required; exploitation can crash the router or corrupt control data, while code execution is not demonstrated.
The record
- CVE
- CVE-2025-6121
- Published
- Jun 16, 2025
- Updated
- Jun 16, 2025
- Vendor
- D-Link
- Product
- DIR-632
- Classifications
- CWE-119, CWE-121, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 16, 2025CVE publishedPublication date reported by the CVE source.
- Jun 16, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=FW103B08
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- DIR-632 negative Content-Length proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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