Code execution via decoder SEH overwrite
Published Feb 5, 2026 · Updated Feb 5, 2026
Stack-based buffer overflow in 4Mhz Base64 Decoder 1.1.2 allows attackers to execute arbitrary code through crafted Base64 input. The decoding path writes oversized pasted input beyond a stack buffer, allowing the payload to overwrite Structured Exception Handler control data and redirect execution to an egg hunter. Exploitation requires the input to be pasted into the search box and Decode to be clicked; successful control-flow hijacking runs code with the application's privileges.
Summary
What happened
Stack-based buffer overflow in 4Mhz Base64 Decoder 1.1.2 allows attackers to execute arbitrary code through crafted Base64 input. The decoding path writes oversized pasted input beyond a stack buffer, allowing the payload to overwrite Structured Exception Handler control data and redirect execution to an egg hunter. Exploitation requires the input to be pasted into the search box and Decode to be clicked; successful control-flow hijacking runs code with the application's privileges.
The record
- CVE
- CVE-2020-37124
- Published
- Feb 5, 2026
- Updated
- Feb 5, 2026
- Vendor
- 4Mhz
- Product
- Base64 Decoder
- Classifications
- CWE-121, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 5, 2026CVE publishedPublication date reported by the CVE source.
- Feb 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.1.2
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
- B64dec 1.1.2 Buffer Overflow SEH Overflow and EggHunterfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo